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Digitized  by  the  Internet  Archive 

in  2010  with  funding  from 
Columbia  University  Libraries 


http://www.archive.org/details/veterinarysurgeOOmeri 


lo  Mr.  MYRON  H.    TICHENOR  and   Mr.    LOUIS  M.    NEWCAS,    ot 

Chicago,  U     S.    A.,   for  their  appreciation    of  the   valuta  ^r  animal 

dentistry   on   valuable  coach  and  saddle  horses,  this  volume  is  re 

spectfully  dedicated  by 

The  Author 


VETERINARY  SURGERY 

Py  Louis  A.  Merillat,  V.  S. 
Volume  I 


ANIMAL  DENTISTRY  AND  DISEASES  OF 
THE  MOUTH 


VETERINARY  SURGERY 

By  LOUIS  A.  MERILLAT,  V.  S. 


Volume  I 
ANIMAL  DENTISTRY  AND  DISEASES  OF  THE  MOUTH 


Volume  II 
THE  PRINCIPLES  OF  VETERINARY  SURGERY 


Volume  III 


VETERINARY  SURGICAL  OPERATIONS 


IDeterinari?  Suraerp 

Volume  I. 


ANIMAL  DENTISTRY 


AND 


DISEASES  OF  THE  MOUTH 


Louis  A.  Merillat.  V.  S. 


AUTHOR    OF    "PRINCIPLES    OF   VETERINARY    FTJRGERY"    AND    "VETERINARY 
SI'RGICAL       OPERATIONS";       COLLABORATOR       AMERICAN      VETERINARY 
REVIEW;    PROFESSOR    OF   SURGERY    IN    THE    McKILLIP    VETERINARY 
COLLEGE;      LATE      PROFEP'SOR     OF     SURGERY     IN     THE     CHICAGO 
VETERINARY    COLLEGE;    LATE    PRESIDENT    OP   THE    CHICAGO 
VETERINARY    SOCIETY:    LATE    SECRETARY    OF    THE    ASSO- 
CIATION   OF    FACULTIES    AND    EXAMINING    BOARDS    OF 
NORTH       AMERICA;       VICE-PRESIDENT       AMERICAN 
VETERINARY     MEDICAL     ASSOCIATION, 
ETC.,    ETC..    ETC, 


1Hlu0trate5 


CHICAGO 

ALEXANDER  EGER 
1914 


2-7-3.2. /r<3 


Entered  according  to  Act  of  Congress,  in  the  year  190R.  hv 

ALEXANDER  EGER 

;n  ♦he  office  of  the  Librarian  of  Congress  at  Washington. 


PREFACE. 

The  domain  of  animal  dentistry  is  too  limited  to  fill  a 
large  volume  without  entering  into  the  details  of  embryol- 
ogy, anatomy  and  physiology,  and  since  these  sciences  are 
today  ably  covered  by  w^riters  possessing  special  merit  in 
each,  it  would  appear  ridiculous  for  a  veterinary  practitioner 
to  "venture  where  angels  fear  to  tread."  A  comprehensive 
understanding  of  the  teeth  in  their  normal  state  at  the  dif- 
ferent periods  of  life,  as  a  foundation  for  the  intelligent  treat- 
ment of  their  abnormalities  is,  however,  so  essential  that  it 
has  been  thought  advisable  to  include  an  epitome  of  these 
sciences  so  far  as  they  appertain  to  the  teeth. 

This  Volume,  with  Volumes  II  and  III,  is  written  at  the 
earnest  solicitation  of  the  students  I  have  had  the  privilege 
of  teaching  during  the  past  twelve  years,  which  circumstance 
is  the  only  excuse  for  its  publication.  The  fact  that  animal 
dentistry  is  given  but  limited  space  in  the  surgical  litera- 
ture of  the  profession  has  not  entered  into  the  proposition, 
because  the  task  of  writing  books  belongs  to  those  having 
the  time  and  inclination  to  ponder  leisurely  over  each  single 
topic,  and  not  to  the  busy  practitioner,  whose  few  idle 
moments  are  usually  interrupted  by  "a  call  to  action." 

It  has  been  the  aim  to  cover  the  subject  in  a  matter-of- 
fact  manner,  excluding  all  obscure,  rare  and  imaginary  con- 
ditions and  including  all  the  conditions  encountered  in  the 
routine  of  practice.     For  compiling  the  index  and  for  the 

illustrations,  which  arc  made  from  copies  and  original  draw- 

ix 


3f  PREFACE. 

ings,  I  am  particularly  indebted  to  Mr.  Alex.  I*lger.  I  have 
also  to  thank  my  friend,  Dr.  W.  L.  Williams,  Professor  of 
Surg-ery  in  the  New  York  State  Veterinary  College,  for  his 
valuable  suggestions  as  to  the  origin  of  teratomata  of  the 
mastoid  region,  and  my  brother  Professor,  Edw.  Merillat, 
for  his  many  original  ideas  which  are  entered  throughout 
the  text  with  but  a  single  credit,  viz.,  the  operation  for  clos- 
ing skull  perforations. 

With  a  full  knowledge  that  the  manuscript  would  crum- 
ble from  the  assault  of  a  literary  critic,  I  forthwith  apologize 
to  the  censors  of  English  veterinary  literature. 

L.  A.  MERILLAT. 


CONTENTS. 


PAGE 

Preface ix 

Introduction 13 

Chapter  I 18-43 

Nomenclature  of  Teeth 18 

Divisions  of  a  Tooth 19 

Structures  of  the  Teeth 20 

Chapter  II  44-67 

Evolution  of  the  Teeth 44 

Embryonic  Evolution 44 

Evolution  of  the  Temporary  Teeth 49 

Evolution  of  the  Permanent  Teeth 58 

Chapter  III 68-126 

Retrogression  of  the  Temporary  Teeth 68 

Retrogression  of  the  Permanent  Teeth 68 

Determination  of  Age 74 

Routine  of  Examination  of  a  Horse's  Mouth  to  Determine  Age 113 

Anomalies  of  the  Teeth,  Natural  and  Artificial.... 117 

Chapter  IV 127-132 

Function  of  the  Teeth 127 

Chapter  V 133-151 

Dental  Diagnosis 133 

Dental  Instruments — Their  Uses 135 

Restraint 148 

Chapter  VI 152-256 

Diseases  and  Irregularities  of  the  Teeth 152 

Necrosis  of  the  Teeth  of  Herbivora 152 

Caries 172 

Abnormal  Eruptions  of  the  Teeth 175 

Dental   Cysts 177 

Odontomata 178 

Brachygnathism 179 

Prognathism 181 

Parvignathism  182 

Projections  on  First  Superior  and  Sixth  Inferior  Molars 184 

Projections  on  the  Superior  Corners 185 

Acquired  Elongations  of  the  Molars 185 

Enamel    Points 187 

Wolf  Teeth 202 

xi 


xii  CONTENTS. 

PAGE 

Supernumerary  Teeth 204 

Elongation  of  Incisors 207 

Erosion  of  Enamel 208 

Tartar 208 

Fracture  of  the  Teeth 209 

Splitting  of  the  Molars 209 

Foreign  Bodies  in  the  Mouth 210 

Fracture  of  the  Inferior  Maxilla .-....•... 211 

Fractures  of  the  Pre-Maxilla  and  Superior  Maxilla 213 

Dislocation  of  the  Temporo-Maxillary  Articulation..' 213 

Bit  Gnathitis 214 

Osteomata  of  the  Superior  Maxilla 21G 

Carcinomata  of  the  Palate 217 

Sarcomata  of  the  Mouth 217 

Actinomycosis 218 

Dental  Teratomata .„ 222 

Dental  Fistulae  :. 224 

Traumatic  Stomatitis 226 

Stomatitis — Infectious 227 

Ulcerative  Gingivitis  of  Dogs 229 

Retention    Cysts 230 

Lampas 230 

Secondary  Chronic   Nasal  Catarrh 231 

Chronic  Perforation  of  the  Skull 236 

Application  of  Gutta  Percha  Plugs 238 

Cribbing  and  Wind-Sucking .^ 239 

Habitual  PtyaHsm 241 

Side-Reining 242 

Habitual  Protrusion  of  the  Tongue 244 

Bit  Lugging 245 

Facial  Paralysis 248 

Lacerations  of  the  Lips 249 

Ranula ■ 250 

Foreign  Bodies  in  the  Tongue 250 

Frost  Bites,  Laceration  of   the  Cheeks  and  Tumors  of  Lips  and 

Cheeks - 251 

Laceration  and  Inflammation  of  Tongue , 252 

Aberrations  of  the  Function  of  Mastication 253 


INTRODUCTION. 

Dentistry  is  the  art  of  repairing  the  teeth  or  improving 
their  utihty.  Human  dentistry  embraces  the  art  of  supply- 
ing artificial  substitutes  for  the  teeth  when  the  original  ones 
are  lost,  while  animal  dentistry  includes  the  therapeutics  of 
the  secondary  pathological  processes  and  lesions  in  the 
mouth  and  nasal  cavities,  caused  by  the  teeth.  It  is,  however, 
essentially  a  mechanical  rather  than  a  surgical  departure, 
and  a  preventive  rather  than  a  curative  effort.  Its  province 
ends  with  the  teeth  and  their  immediate  environs.  Dis- 
orders of  the  digestion  or  impairment  of  the  general  health, 
although  directly  traceable  to  the  teeth,  cannot  be  included 
within  the  domain  of  dentistry.  The  principal  object  of 
dentistry  is  to  promote  the  general  health  by  improving  the 
mastication  and  by  relieving  pain.  It  also  aims  at  the  pre- 
servation of  the  juvenile  appearance,  to  which  the  animal 
dentist  adds  the  amelioration  of  the  driving  defects  of 
horses. 

Human  dentistry  owes  its  existence  to  a  single  disease 
process,  caries,  while  animal  dentistry  depends  upon  a  single 
physical  defect,  enamel  points.  Without  these  two  abnor- 
malities dentistry  w^ould  never  have  existed  as  an  advanced 
art;  no^  because  there  are  no  other  serious  abnormalities 
within  the  domain  of  dentistry,  but  because  other  abnormali- 
ties are  infrequent.  Few  mature  human  beings  escape  caries, 
and  few  mature  herbivora  escape  enamel  points.  Hence  the 
wide  requirement  for  dental  operations  in  the  human  family, 
and  in  the  chief  domestic  animal — the  horse.  As  the  extrac- 
tion, replacement  and  repair  of  the  decayed  tooth  is  the  chief 
occupation  of  the  human  dentist,  so  is  cutting  and  floating 

18 


14  ANIMAL  DENTISTRY. 

enamel  points  the  princi]);!!  work  of  the  animal  dentist.  No 
student  of  zooloj;-y  will  deny  that  the  domestic  herbivora, 
especially  the  horse,  suffers  from  frii^htful  physical  defects 
that  are  inimical  to  their  <^eneral  health  and  usefulness.  The 
other  defects  and  diseases,  althouj^h  frequently  of  serious 
import,  demand  only  a  small  share  of  the  animal  dentist's 
attention  because  they  are  relatively  rare.  The  porcine, 
ovine,  and  bovine  species  do  not  suffer  to  the  same  extent 
as  the  domestic  horse  on  account  of  their  different  occupa- 
tion and  short  life.  Except  for  breeding-  purposes  these 
genera  seldom  live  beyond  their  maturity,  and  even  then 
they  are  not  submitted  to  the  same  artificial  influences  as  the 
horse.  In  the  canine  and  feline  species  the  anatomical  con- 
stitution of  the  teeth  prevents  projecting  defects  and  their 
short  life  precludes  caries,  so  here  again  the  animal  dentist 
meets  only  an  occasional  condition  demanding  attention. 
It  is  evident,  therefore,  that  animal  dentistry  naturally  cen- 
ters upon  the  horse,  the  commercial  value  of  which  depends 
as  much  upon  its  utiHty  as  upon  its  general  appearance. 
And  again,  mastication  and  insalivation  are  two  essential 
digestive  processes  in  herbivora,  and  of  more  relative  impor- 
tance than  in  carnivora  and  omnivora.  The  coarse  amy- 
laceous food  of  herbivora,  especially  the  non-ruminating  her- 
bivora, requires  immediate  and  perfect  comminution  and 
incorporation  with  saliva  to  insure  perfect  gastric  digestion 
and  subsequent  absorption,  while  the  artificially  prepared 
food  of  man  may  without  special  detriment  be  passed  di- 
rectly to  the  stomach  with  but  little  mastication.  The  same 
may  be  said  of  the  dog,  the  cat  and  the  hog,  all  of  which 
consume  their  food  without  a  semblance  of  persistent  mas- 
tication. 

Then  again,  animal  dentistry  must  respect  the  horse's 
mouth  as  the  "seat  of  the  bit"  as  well  as  the  mechanism  of 
mastication.    The  manner  in  which  the  horse  accepts  the  bit 


ANIMAL  DENTISTRY 


15 


must  always  be  a  determining  factor  in  its  value.  The 
dental  defects  which  irritate  or  wound  the  buccal  surfaces 
under  the  pressure  of  the  complicated  rig-gings  of  harness 
and  saddle  horses  constitute  an  important  feature  of  animal 
dentistry. 

A  summary  of  the  exact  scope  of  animal  dentistry  is  as 
follows : 

1st.  The  cutting  and  floating  of  the  enamel  points  of  the 
horse  and  ox. 

2nd.  The  removal  of  projections  which  prevent  perfect 
apposition  of  the  dental  arcades  of  the  horse,  ox  and  hog. 

3rd.  The  treatment  of  secondary  nasal  catarrh  resulting 
from  diseased  teeth. 

4th.     The  extraction  of  all  diseased  teeth  of  all  animals. 

5th.  The  removal  of  tumors  related  to  the  teeth,  in  all 
animals. 

6th.  The  treatment  of  stomatitis  caused  by  the  bit  or  by 
dental  projections. 

7th.  The  amelioration  of  driving  defects  resulting  from 
dental  irregularities  in  the  horse. 

8th.  The  treatment  of  faulty  eruptions  of  the  perma- 
nent or  temporary  dentures  in  the  dog,  the  horse,  the  ox  and 
the  cat. 

9th.  Improving  the  appearance  of  the  incisors  of  the 
horse. 

When  dentistry  in  animals  is  more  generally  recognized 
as  an  important  if  not  essential  feature  of  animal  therapeu- 
tics, and  when  dental  operations  by  reason  of  greater  skill 
are  made  easier,  the  veterinarian  will  then  treat  the  art  of 
dentistry  with  the  same  dignity  as  the  other  branches  of 
surgery.  One  object  of  this  volume  is  to  popularize  the  art 
of  animal  dentistry  by  describing  easy  methods  of  perform- 
ing dental  operations;  by  drawing  attention  to  the  value  and 
necessity  of  dentistry,  and  by  pointing  out  the  advisability 


16  ANIMAL  DENTISTRY. 

of  sacredly  i^iiardinc;-  dentistry  from  hecominj^  obsolete  in 
the  veterinary  profession,  and  from  passini^  to  the  willing 
specialist,  who.  throu.^h  deficient  fundamental  technical  edu- 
cation cannot  keep  pace  with  the  advancement  continually 
being  made  in  the  other  branches  of  veterinary  surgery. 
Animal  dentistry  is  unpopular,  not  so  much  because  it  is 
difficult,  tedious  and  even  dangerous,  but  because  it  is  re- 
garded as  of  minor  importance  in  the  veterinary  colleges 
and  l)y  the  better  class  of  veterinary  practitioners,  who  will- 
ingly stigmatize  animal  dentistry  as  an  unimportant  "side 
issue"  by  relegating  dental  operations  to  the  student,  the 
assistant,  the  stable-helper,  the  horse-shoer  or  the  horse- 
dentist. 

Only  a  few  years  ago,  at  the  urgent  request  of  a  suffering 
patient,  the  family  physician  would  condescend  to  pull  an 
aching  tooth,  but  he  was  never  specially  provoked  if  such  a 
patient  had  consulted  the  watchmaker  or  the  locksmith,  who 
in  many  localities  had  earned  enviable  reputations  as  expert 
tooth-pullers,  and  who  finally  became  the  first  recruits  in  the 
new  profession  of  human  dentistry.  The  duty  of  the  veteri- 
narian of  today  toward  the  tooth-rasping  horse-shoer  or  the 
professional  horse-dentist  bears  a  striking  resemblance  to 
the  relations  between  the  physician  and  tooth-pulling  lock- 
smith of  a  few  years  ago.  The  able  physician  in  those  days 
willingly  consigned  the  tooth-ache  patient  to  the  locksmith, 
or  the  barber,  or  the  watchmaker,  because  dental  operations 
were  then  considered  as  an  unimportant  "side  issue,"  rather 
beneath  the  dignity  of  the  learned  therapeutist.  But,  in 
spite  of  this  apathy,  dentistry  asserted  its  importance  and 
soon  became  a  part  of  the  curriculum  of  the  foremost  uni- 
versities of  the  world. 

This  is  precisely  the  status  of  animal  dentistry  today. 
The  veterinarian  consigns  dental  operations  to  others  be- 
cause it  is  rather  beneath  the  dignity  of  the  learned  veteri- 


ANIMAL  DENTISTRY.  I7 

narian  to  float  the  teeth  of  horses ;  not  because  it  is  difficult, 
tedious  or  dangerous,  but  because  animal  dentistry  is  re- 
garded as  a  trifling  accomplishment  that  the  uneducated  can 
master.  The  intimate  relation  of  the  condition  of  the  teeth 
to  the  general  health  is  becoming  more  and  more  recognized, 
and  when  the  value  and  importance  of  veterinary  dentistry  is 
universally  recognized  by  the  veterinary  profession  and  lay 
public,  and  when  it  becomes  more  generally  admitted  on  all 
sides  that  the  veterinary  patient  receives  the  same  relative 
benefits  from  dental  operations  as  the  human  subject,  animal 
dentistry  will  then  take  its  place  among  the  useful  branches 
of  veterinary  science.  The  limited  number  of  patients  will 
probably  always  prevent  the  evolution  of  animal  dentistrv 
into  a  special  profession.  The  veterinarian  will,  therefore, 
be  required  to  perfect  himself  in  the  practice  of  this  art. 

There  were  two  potent  factors  concerned  in  the  evolu- 
tion of  human  dentistry — the  college  and  the  practitioner. 
The  same  influences  are  essential  to  the  healthy  evolution  of 
animal  dentistry.  The  college  must  devote  more  time  to 
the  art  and  the  practitioner  must  become  more  proficient, 
even  though  the  increasing  importance  of  animal  dentistry 
cannot  be  met  by  the  birth  of  a  new  profession.  The  subject 
deserves  to  be  brought  out  more  prominently  in  the  litera- 
ture on  surgical  subjects,  in  order  to  foster  and  maintain  its 
sesqui-special  relations  to  veterinary  surgery  as  a  whole. 


CHAPTER  I. 

NOMENCLATURE  OF  THE  TEETH. 

The  teeth  are  called.  Incisors,  Canines,  or  Molars,  ac- 
cording to  their  location,  form  and  function  ;  they  are  supe- 
rior or  inferior  accordin^^  to  the  jaw  into  which  they  are  im- 
planted ;  and  right  or  left  according  to  the  side  of  the  median 
line  of  the  body  they  occupy.  The  incisors,  naming-  from  the 
median  line  outward,  are  called  centrals,  laterals  and  cor- 
ners.    The  molars  are  numbered,   ist,   2nd,  3rd,   etc.,  from 


Fk;.   I. 
Complete  Denture  of  a  Horse. 

1.  The  Canine  denture. 

2.  Incisor  denture. 

3.  Molar  denture. 

before  backward.  The  sul)di vision  of  the  molars  into  pre- 
molars and  molars  is  useless  in  the  herbivora,  as  they  pos- 
sess no  distinguishing  characteristics  that  would  warrant 
such  classification,  and  in  the  other  animals  the  subdivision 
is  more  confusing  than  instructive. 

Each  tooth  in  the  head  ma}-  then  be  identified  by  refer- 

18 


ANIMAL  DENTISTRY.  19 

ring  to  it  as  the  "right-first-superior  molar,"  the  "left- 
fourth-siiperior  molar,"  the  "left-inferior-lateral,"  or  the 
"left-inferior  canine,"  etc.,  throughout  the  dental  arcades. 

DIVISIONS  OF  A  TOOTH. 

Anatomically  a  tooth  is  divided  into  the  crown,  neck, 
fang,  roots,  table,  infundibulum  and  cup.  The  crown  refers  to 
the  projecting  portion,  or  in  other  words  that  part  of  a  nor- 
mal tooth  that  is  visible.  The  neck  is  the  part  covered  with 
gums,  or  the  part  between  the  crown  and  alveolar  margin. 
The  fang  is  the  imbedded  portion  or  the  part  between  the  al- 
veolar margin  and  the  projecting  roots.  The  roots  are  the 
small  projections  at  the  imbedded  extremity  of  the  fang. 
The  table  refers  to  the  grinding  or  contact  surface.  The 
infundibulum  is  the  cavity  on  the  table  produced  by  the  in- 
folding of  the  enamel,  while  the  cup  refers  to  the  unfilled 
portion  of  the  infundibula  of  the  incisors. 

The  surfaces  of  the  teeth  are  frequently  referred  to  as  the 
"buccal  surface,"  the  "labial  surface,"  or  the  "lingual  sur- 
face." In  the  case  of  the  molars  the  buccal  surface  is  the 
external  and  the  lingual,  the  internal,  while  in  the  incisors  the 
lingual  refers  to  the  posterior  surface,  and  the  labial  to  the 
anterior. 

Other  names  frequently  used  in  the  study  of  dentistry  are 
"alveolar  margin,"  referring  to  the  outer  border  of  the  alveo- 
lar cavity ;  the  "gingival  margin,"  which  refers  to  the  outer 
border  of  the  gums,  and  "contact  margin,"  which  implies 
the  cutting  border  of  a  tooth  such  as  an  incisor  of  carnivora. 

STRUCTURES  OF  THE  TEETH. 

A  tooth  is  composed  of  hard  and  soft  tissues,  of  which 
the  former  predominates  in  volume  and  importance.  The 
hard  tissues  comprise  a  body  of  dentine,  capped  with  enamel. 


20 


ANIMAL    l)i;.\'l"l.S'r]<V 


and  encrusted  over  the  remaining  portion  with  crusta  pe- 
trosa,  or  cement.  Tlic  soft  structures  arc  the  pulp,  which 
occupies  a  cavity  within  tlie  Ixxly  of  the  tootli.  the  aveolo- 
dental  periosteum  which  surrounds  the  external  surface  of 
the  fang,  the  gums  or  gingivae,  whicli  cover  the  neck,  the 
blood  vessels  which  supply  its  nutrition,  and  the  nerves 
which  furnish  its  sensihilitv  and  tactile  sense. 

DENTINE. 
The  dentine  is  a  hard,  yellowish,  sensitive  substance  con- 


Enanul  and  Dentine  as  Arranged  at 
the   Crown. 

1.  Enamel. 

2.  Spaces  of  Czermak. 

3.  D'entii>e. 

(Magnified.) 


Fig.  2. 

Dentinal  Tubules.  Magnified. 


stituting  the  major  portion  of  the  tooth's  volume.  It  ex- 
tends from  the  pulp  cavity  within  to  the  enamel  and  crusta 
petrosa  without.  Chemically  it  shows  the  following  compo- 
sition : 

Carbonate  of  lime 7.97 

Phosphate  of  lime ^V-54 

Phosphate  of  magnesia 2.49 

Fluoride  of  lime   a  trace 


ANIMAL   DENTISTRY.  -J»l 

Fats    58 

Cartilage    20.42 

Soluble  salts    i. 

jMicroscopically  it  reveals  a  homogeneous  substance  per- 
forated throughout  with  small  canals  (the  dentinal  tubules) 
which  anastomose  freely  with  each  other  and  extend  out- 
ward from  the  pulp  cavity  to  the  surface  where  they  termi- 
nate in  large  lacunae  (the  spaces  of  Czermak),  which  in 
turn  communicate  with  the  canaliculi  of  the  crusta  petrosa 
at  the  fang,  and  cuticle  of  the  enamel  at  the  crown.  The 
tubules  are  from  four  to  five  microns  in  diameter  at  the  pulp 
cavity,  and  one  to  two  microns  at  the  surface  of  the  dentine. 

ENAMEL. 


The  enamel  is  the  hardest  of  the  dental  tissues  contain- 
ing more  than  96  per  cent  of  inorganic  matter.  It  is  ar- 
ranged upon  the  dentine  in  the  form  of  a  thin  cap  over  the 
crown  and  extending  beyond  the  alveolar  margin  over  a 
part  of  the  fang.     In  the  herbivorous  animals  it  is  deeply 


FlG.   3. 
Enamel    (Magnified). 


Fig.  4. 

The    Enamel   Organ   Dissected   from 

the   First  INIolar  of  a   Small 

Ruminant. 


folded  into  the  table  to  form  the  well  known  depression 
characteristic  of  these  teeth,  the  infundibulum.  In  the  virgin 
tooth  it  covers  the  entire  talkie  surface,  but  soon  wears  off  at 
that  point  from  the  mastication  of  food,  leaving  only  its 
edges  projecting  at  the  grinding  surface.  In  the  incisor 
teeth  it  is  the  outer  covering  of  both  the  labial  and  lingual 
surfaces,  throughout  the  life  of  the  animal,  but  in  the  molars 


22  ANIMAL   DENTISTRY. 

it  soon  becomes  thickly  encrusted  witli  cnista  petrosa  on 
both  the  buccal  and  lingual  surfav:es.  'J'hc  molar  teeth  have 
no  outer  enamel  covering  after  they  have  been  in  wear  for 
a  short  time.  'I'hc  enamel  surrounding  the  iiifundibula  of 
the  incisors  is  arranged  in  llic  fcjrm  of  ;in  oblong  or  ellii:)tical 
ring  at  the  tabic  surface,  while  that  of  the  molars  is  folded 
into  a  \cry  irregular  boundary.  The  external  enamel  con- 
sists of  an  undulated  plate  following  the  course  of  the  longi- 
tudinal ridges  and  grooves  of  the  molar  teeth.  At  the  table 
end  of  the  longitudinal  ridges  it  terminates  in  a  sharp  point, 
constituting  the  "sharp  teeth"  of  herbivora.  Chemically,  it 
consists  of : 

Carbonate  of  lime 4.37 

Phosphate    of    lime 89.82 

Fluoride  of  lime    a  trace 

Phosphate   of   magnesia 1.34 

Soluble  salts    88 

Organic  matter    3.59 

Microscopically  it  jM'csents  a  thin  cuticle  or  skin  called 
the  cuticle  of  the  enamel,  which  is  separable  when  a  section 
of  enamel  is  treated  ^vith  hydrochloric  acid,  and  hexagonal 
prisms  projecting  at  a  right  angle  from  the  surface  of  the 
dentine,  giving  the  appearance  of  a  mosiac  floor. 

CRUSTA  PETROSA  OR  CEMENT. 

The  crusta  petrosa  is  the  softest  of  the  three  hard  bodies 
composing  the  teeth.  It  is  an  external  osseous  incrustation 
of  the  fang  by  which  the  tooth  is  cemented  to  the  alveolar 
cavity.  In  the  virgin  tooth  it  is  but  a  thin  layer,  but  as  the 
tooth  ages  it  becomes  thick  from  the  deposition  of  osseous 
tissue.  Crusta  petrosa  covers  the  entire  outer  surfaces  of 
the  mature  molars,  the  fangs  of  the  incisors,  the  grooves  in 
the  crowns  of  the  incisors  of  old  animals  and  partly  fills  the 


ANIMAL   DENTISTRY. 


23 


infundibula.     In  animals  having  simple  teeth  it  is  limited  to 
the  fangs.     Chemically,  it  is  composed  of: 

Carbonate  of  lime 7.22 

Phosphate   of   lime 48.73 

Fluoride  of  lime a  trace 

Phosphate  of  magnesia 99 

Soluble  salts    82 

Cartilage    4i-3i 

I^ats    93 

]\Iicroscopically  it  presents  the  typical  characteristics  of 


m0$ 


Fig.  5. 
Dentine  and   Crusta   Petrosa  as   Ar- 
ranged at  the  Fang  (Magnified). 

1.  Crusta  petrosa. 

2.  Spaces  of  Czermak. 

3.  Dentine. 


Fig.  6. 
Natural  Cavities  of  a  Molar. 

A.  Pulp  cavity. 

B.  Infundibulum, 


the  compact  tissue  of  bone,  the  canaliculi  of  which  communi- 
cate with  those  of  the  dentine.  It  is  intimately  associated 
with  the  alveolo-dental  periosteum,  which  membrane  is  con- 
cerned in  its  formation. 


24 


ANIMAL    DENTISTRY. 


THE  PULP. 

The  pulp  is  a  pultaceous  substance  molded  to  the  snape 
of  the  pulp  cavity,  consisting  of  loosely  arranged  connective 
tissue,  blood  vessels,  nerves  and  a  limiting  membrane 
(odontogenic  membrane)  which  sends  processes  through- 
out the  entire  length  and  course  of  the  dentinal  tubules,  and 
communicates  with   the   alveolo-dental     periosteum     at   the 


Fig.  7. 
Arrangement  of  the  Dental   Tissues  in  an   Incisor. 

1.  Internal  enamel  surrounding  the  infundibulum. 

2.  Pulp. 

3.  Dentine. 

4.  External  enamel. 

apical  foramen.  The  pulp  itself  acts  as  a  support  for  the 
blood  vessels  and  nerves  while  the  odontogenic  membrane 
is  concerned  in  tooth  construction.  In  the  teeth  of  herbivora 
it  is  constantly  depositing  dentinal  substance  in  the  tubules 
beneath  the  table  surface  to  destroy  the  sensibility  of  the 
wearing  dentine. 


ALVEOLO-DENTAL  PERIOSTEUM. 

The  alveolo-dental  periosteum  is  a  dense,  tough  mem- 
brane consisting  chiefly  of  white  fibrous  tissue  and  osteo- 
blasts. It  covers  the  entire  fang,  communicates  with  the 
limiting  membrane  of  the  pulp  at  the  apical  foramen,  and  in- 
termingles   intimately   with   the    gums    at    the    neck    of   the 


ANIMAL   DENTISTRY.  25 

tooth.  Its  fibers  are  continuous  with  the  stroma  of  the 
crusta  petrosa  and  that  of  the  alveolar  wall,  forming  a  firm 
connecting-  medium  between  the  two.  In  the  virgin  tooth 
it  has  all  the  characteristics  of  a  membrane,  but  it  soon  loses 
this  feature  and  becomes  confused  with  the  crusta  petrosa, 
which  tissue  it  develops. 

THE  GUMS. 

The  gums,  or  gingivae,  may  be  considered  in  the  sense 
of  a  hypertrophy,  either  of  the  buccal  mucous  membrane  or 
of  the  alveolo-dental  periosteum,  to  both  of  which  they  are 
intimately  connected.  They  consist  of  dense  fibrous  tissue, 
the  fibers  of  which  intermingle  with  the  alveolo-dental  peri- 
osteum and  crusta  petrosa,  with  the  purpose  of  hermetically 
sealing  the  alveolar  cavities  from  external  influences. 

BLOOD  VESSELS. 

The  blood  supply  of  the  teeth  is  derived  from  the  su- 
perior and  inferior  dental  arteries,  branches  of  the  external 
carotid.  The  superior  dental  is  given  of¥  the  internal  maxil- 
lary, passes  into  the  superior  dental  foramen  of  the  maxil- 
lary hiatus,  through  the  superior  dental  canal  as  far  as  the 
infra-orbital  foramen,  along  the  roots  of  the  third,  second 
and  first  molars,  and  then  through  the  premaxilla  to  the  ca- 
nines and  incisors.  Along  the  course  of  the  dental  arcades 
it  gives  ofT  branches,  for  each  tooth,  which  pass  into  the 
pulp  cavity  through  the  apical  foramina.  The  inferior  den- 
tal artery  has  the  same  general  distribution  via  the  inferior 
dental  canal.  In  addition  to  this  principal  blood  supply  teeth 
receive  nourishment  from  surrounding  blood  vessels  by 
way  of  the  alveolo-dental  periosteum  to  the  extent  of  pre- 
serving the  integrity  of  the  tooth  should  its  principal  supply 
be  interrupted. 


26 


ANIMAL  DENTISTRY. 


THE  NERVES. 


The  nerves  are  sensory  and  tactile,  and  are  derived  from 
the  superior  and  the  inferior  maxillary  branches  of  the  tri- 


J-K..    y. 

Incisor  and  Canine  Teeth  of  a   Mature   I  lorse. 


28  ANIMAL   DENTISTRY. 

facial.     They  have  the  same  general  distribution  as  the  ar- 
teries, the  courses  of  whicli  they  follow  into  the  pulp  cavity. 


Fig.  10. 
Incisor  Tectli   of  a   Mature  ITcrsc,  Anterior  View. 

PERMANENT  INCISOR  TEETH  OF  A  HORSE. 

The  incisor  tooth  of  a  horse  presents  the  form  of  a  curved 
pyramid  with  the  greater  curvature  forward,  the  base  out- 
ward and  the  apex  implanted  deeply  into  the  alveolar  cavity 


ANIMAL    DENTISTRY 


29 


of  the  same  shape.  The  base  of  the  pyramid,  which  repre- 
sents the  crown,  is  elliptical,  and  measuring  toward  the  apex 
it  becomes  first  oblong,  then  triangular,  then  rounded  and 
finally  biangular  in  the  antero-posterior  direction.  At  the 
table  it  presents  the  external  enamel  dentine,  internal 
enamel,  and  infundibukim.     The  labial  and  lingual  surfaces 


Fig.  II. 
Canine  T'eeth  of  a  Horse,  Buccal  Sur- 
face. 


Fig.  12. 

Ganine    Teeth    of    a    Horse,    Lingual 

Surface. 


Fig.   1-3. 
Longitudinal    Sections   Throu.ti^li    Incisor   Teeth. 

are  covered  with  enamel  which  in  youth  is  uninterrupted 
with  encrustations  of  either  tartar  or  crusta  petrosa,  and  is 
of  a  bluish-white  color.    At  the  apex  it  presents  a  wide  o/en- 


30  ANIMAL    DENTISTRY 

iiii^-— the  apical  foramen — for  the  cnlrancc  of  blood  vessels 
and  nerves. 

In  situ  tlicy  are  arranged  in  perfect  juxtaposition  in  the 
form  of  a  symmetrical  curve  with  the  convexity  forward, 
and  tlieir  contact  with  the  opposing  arcade  is  at  an  obtuse 
angle.  Near  the  gingival  margin  they  are  separated  by 
processes  of  the  gums.     (See  Fig.  lo.) 

The  function  of  the  incisor  teeth  is  that  of  detaching  food 
th.at  has  l)een  gathered  by  the  lips,  and  to  serve  as  weapons 
of  defense,  l^hey  are  not  concerned  in  mastication.  For 
changes  in  the  teeth,  see  Chajjter  ITT. 

THE  CANINE  TEETH  OF  THE  HORSE. 

The  canine  teeth  exist  only  in  males  and  occur  only  as 
permanent  teeth.  They  occur  occasionally  as  rudimentary 
structures  in  the  mare,  but  never  develop  the  typical  canine 
characteristics.  They  represent  a  curved  tube  about  one 
centimeter  in  diameter,  and  flattened  at  one  end — the  crown. 
The  crown  is  flat  and  presents  internally  two  shallow  per- 
pendicular grooves  dixided  by  a  rounded  ridge.  The  fang 
is  cylindrical  and  the  apical  foramen  round  and  large. 

The  canines,  so  far  as  digestion  is  concerned,  are  use- 
less members  which  the  horse  could  well  do  without.  They 
are  pro1)al)ly  intended  as  weapons  of  defense,  and  may  serve 
to  assist  in  passing  coarse  fibrous  food  from  the  incisors  to 
the  molars. 

THE  MOLARS. 

The  superior  molars  resemble  an  elongated  square  block 
tapering  slightly  toward  one  extremity.  They  present  for 
description  four  surfaces,  the  table  and  apex.  The  external 
or  buccal  surface  presents  three  prominent  longitudinal 
ridges  separated  by  two  grooves,  all  of  which  traverse  the 
entire  length  of  the  tooth,  and  terminate  at  the  table  in  a 


ANIMAL    DENTISTRY. 


31 


sharp  point.  The  anterior  and  posterior  surfaces  are  flat  and 
smooth  and  come  in  contact  with  contiguous  surfaces  at  the 
crown  only.  The  internal  surface  is  quite  smooth  and  some- 
what convex  from  before  backward.  The  table  presents 
the  external  crusta  petrosa,  the  external  enamel,  the  den- 
tine, the  internal  enamel,  and  the  internal  crusta  petrosa. 
The  edges  of  the  enamel  are  arranged  in  the  form  of  the 
letter  *'B."     (See  Figs.  i6,  17.)     In  the  center  of  the  internal 


Fig.  14.  Fig.  15. 

A  Superior  Molar,  Buccal  Surface.         A  Superior   IMoIar,   Lingual   Surface, 

.  with    Measurement. 

crusta  petrosa  is  a  small  black  spot  marking  the  only  open- 
ings of  the  infundibula, which  are  two  in  number  on  all  the 
superior  molar  teeth.  The  apex  presents  three  to  four  roots. 
each  having  a  round  opening — the  apical  foramen.  The  first 
molar  is  triangular  in  shape,  has  a  sharp  anterior  face  and 
presents  but  three  roots  at  the  apex.  The  sixth  is  also 
somewhat  triangular  with  its  acutcst  angle  posteriorly,  and 
like  the  first,  has  but  three  roots. 


32 


ANIMAL    DENTISTRY 


The  first  superior  molar  averai^es  48  millimeters  long, 
the  second  55  millimeters,  the  third  jt^  millimeters,  the  fourth 
68  millimeters,  the  fifth  65  millimeters,  and  the  sixth  60  to 
63  millimeters. 

The  inferior  molars  are  somewhat  longer  and  much  more 
flattened  than  the  superior  ones.  In  volume,  tooth  for  tooth, 
the  superior  ones  greatly  exceed  them.  Their  surfaces  are 
smoother,  their  borders  less  distinct,  and  the  longitudinal 
ridges    less    prominent.       The    longitudinal     ridges    of    the 


WW  S'2 


Fig.  17. 

Arrangement   of   the    Dental    Tissues 

on  the  Table  of  a  Superior 

Molar. 

I,  2.     Infundibula. 

3.  Crusta  petrosa. 

4.  Dentine. 
>.     Enamel. 


internal  or  lingual  surface  are  three  in  number  and  termi- 
nate at  the  tables  in  sharp  enamel  points  similar  to 
the  external  ones  of  the  superior  molars.  The  tables  present 
the  same  dental  substances  as  the  superior,  but  the  enamel 
is  arranged  in  the  form  of  an  irregular  figure,  and  not  in 
the  shape  of  the  letter  "B,"  as  on  the  superior  tables.  The 
enamel  is  but  a  single  organ  and  is  not  divided  into  internal 
and  external  enamel,  as  in  the  incisors  and  superior  molars. 
This  arrangement  leaves  the  inferior  molars  without  per- 
fectly inclosed  infundibula  and  allows  all  the  crusta  petrosa 


ANIMAL    DENTISTRY. 


33 


to  communicate  freely.  This  arrangement  of  the  enamel 
organ  is  due  to  the  fact  that  its  infolds  are  lateral  and  not 
superior.  That  is,  the  enamel  does  not  dip  deeply  into  the 
table  end,  but  folds  inwards  into  great  ruffles  along  each 
side.  They  each  have  two  roots,  each  of  which  is  pierced  at 
the  apex  with  the  foramen  for  the  entrance  of  the  vessels  and 
nerves. 


Fig.   i8. 

Longitudinal  Section 

Through  a  Molar. 

1.  I.     Infundibulum. 

2.  Dentine. 

3.  Crusta  petrosa  and 
enamel. 

4.  Internal  enamel. 


Fig.  ig. 

An  Inferior  Molar, 

Buccal    Surface. 


Fig.  20. 
An  Inferior  Molar,  Lin- 
gual Surface,  with 
Measurement. 

The  superior  arcades  are  prominently  convex  on  the 
external  or  buccal  surface,  and  concave  on  the  internal  or 
lingual  surface.  The  width  of  the  arcade  is  uniform  through- 
out the  entire  length,  with  the  exception  of  the  extremities 
which  taper  to  a  narrow  border  anteriorly  and  a  blunted  one 


34 


ANIMAL   ])ENTISTRY 


posteriorly.  The  width  between  the  arcades  is  83  milli- 
meters at  the  sixth  molars,  75  millimeters  at  the  fourth,  and 
57  millimeters  at  the  first.  They  are  from  18  to  20  centi- 
meters long  and  average  25  to  28  millimeters  wide. 

The  inferior  arcades  arc  more  on  a  straight  line  than  the 
superior  ones.  They  are  but  slightly  curved  outward  at  the 
fourth  and  fifth  molars,  while  at  the  second  and  third  they 
may  even  present  a  slight  inward  curvature.  Like  the  su- 
perior, they  have  a  uniform  width  with  the  exception  of  the 
pointed  extremities.  The  width  between  the  arcades  is  75 
millimeters  at  the  sixth  molars,  60  millimeters  at  the  fourth 
and  about  50  millimeters  at  the  first.  They  are  from  18  to 
20  centimeters  long  and  average  17  to  20  millimeters  wide. 

J7  MM. 


Fig.  20.\. 
Table  Surface  of  an  Inferior  Molar,  with  Measurement. 

In  situ  the  molars  present  four  arcades — right  and  left 
superior  and  right  and  left  infer]f)r — each  containing  six 
teeth,  juxtaposited  so  closely  as  to  give  the  impression  of 
being  a  single  body.  The  juxtaposition  of  the  molars  is  one 
of  the  important  features  of  the  dental  mechanism  of  her- 
bivorous animals.  This  feature  adds  materially  to  the  for- 
mation of  a  perfect,  as  well  as  a  stable,  grinding  apparatus. 

Each  arcade  is  from  18  to  20  centimeters  in  length. 


THE  PERMANENT  INCISORS  OF  RUMINANTS. 

Ruminants  have  but  one  incisor  arcade — the  inferior — 
the  superior  being  replaced  by  a  dense  pad  of  connective 
tissue.     The  incisors  are  eieht  in  number,  identified,  count- 


Fif"'.    21.  Fk;.   22. 

A  Superior  Molar  Arcade  of  a  Horse,       Inferior  Molar   Arcade   of  a   Horse, 

with    Measurement. 

85 


with  Measurement. 


36  ANIMAL   DENTISTRY. 

ing-  from  the  median  line  outward,  as :  centrals,  laterals,  inter- 
mediates, and  corners.  They  resemble  a  scoop  or  shovel  with 
a  taperint;  handle,  are  not  juxtaposed  and  are  always  loose. 
The  fangs  are  imbedded  into  shallow  alveolar  cavaties  and 
the  long-  necks  are  firmly  attached  to  the  gums.  They  are 
very  white  in  color.  The  labial  surface  is  convex  and  the 
lingual  one  concave  to  fit  the  dental  pad  on  the  premaxilla. 
They  diminish  in  size  from  the  centrals  outward,  the  cor- 
ners being  quite  small. 


Fig.  23. 
Incisor   Denture   of  the   Ox. 

THE  PERMANENT  MOLARS  OF  RUMINANTS. 

The  superior  molars  of  the  large  ruminants  resemble 
those  of  the  horse.  They  are  arranged  in  two  arcades  of  six 
molars  each  as  in  solipeds.  The  tables  present  the  enamel, 
internal  and  external,  the  crusta  petrosa,  dentine  and  the 
infundibula.  In  the  three  posterior  molars  the  enamel  is 
arranged  in  the  shape  of  the  letter  "B,"  as  in  the  horse, 


ANIMAL    DENTISTRY. 


37 


while  the  three  anterior  ones  present  more  the  shape  of  a 
"U"  turned  bottom  against  the  tongue.  The  first  three 
molars  have  but  one  infundibulum,  while  the  last  three  have 
two.  The  longitudinal  ridges  are  prominent  features  of  the 
buccal  surface  and  terminate  at  the  table  in  sharp  points. 


Fig.  24. 
Incisor  Teeth  of  the  Ox. 

A.  Lingual  surface  of  lateral  incisor. 

B.  Labial  surface  of  central  incisor. 

C.  Lingual  surface  of  corner  incisor. 

D.  Labial  surface  of   intermediate   incisor. 

The  length  of  the  posterior  molars  is  about  8^^^  centimeters, 
and  that  of  the  anterior  about  5!!'  centimeters.  Each  tooth 
presents  three  roots,  two  of  which  project  externally  and 
one  internally. 

In  situ  they  consist  of  a  continuous  arcade,  narrow  an- 
teriorly and  becoming  gradually  wider  toward  the  posteriq^: 


38 


ANIMAL   DENTISTRY 


Fig.  26. 

Inferior  ]\Iolar  of  an  Ox 

(Labial    Surface). 


Fig.  25. 
A    Superior    Molar    Ar- 
cade of  an  Ox. 


Fig.  27. 

Inferior  Molar  of  an  Ox 

(Lingual  Surface). 


ANIMAL   DENTISTRY.  39 

extremity.  They  cannot  be  said  to  be  as  perfectly  juxta- 
posited  as  in  the  horse,  as  the  internal  surface  of  the  arcades 
has  deep  depressions  at  the  interdentia.  The  arcade  will 
average  12  centimeters  long  and  from  15  to  22  millimeters 
wide. 

The  inferior  molars  are  ver}'-  narrow  and  closely  juxta- 
posited,  as  in  the  inferiors  of  the  horse,  but  in  shape  and 
arransrement  of  the  enamel  each  tooth  differs  from  the  oth- 
ers.  The  first  is  triangular  in  shape  and  contains  but  a  single 
ring  of  enamel.  The  second  and  third  are  rectangular  and 
their  enamel  is  arranged  into  the  form  of  an  irregular  figure 
havino-  five  to  six  indentations.     The  fourth  and  fifth  con- 


FlG.  28. 
Table  of  a   Superior  Molar  of  the  Ox. 

sist  of  two  lobes,  each  having  a  central  enamel  ring  and 
infundibulum,  while  the  sixth  has  three  lobes  with  central 
enamel  infundibula  on  the  two  anterior  lobes.  The  arcades 
measure  from  11  to  15  millimeters  wide.  The  first  three  are 
from  52  to  54  millimeters  long  and  the  posterior  three  meas- 
ure from  88  to  93  millimeters  in  length, 

TEETH  OF  THE  DOG. 

The  dog  has  in  all  forty-two  teeth — six  incisors,  two 
canines  and  six  molars  in  the  superior  jaw  and  six  incisors, 
two  canines  and  seven  molars  in  the  inferior  jaw.  All  of 
the  teeth  of  the  dog  are  simple  teeth,  i.  e.,  they  are  covered 
with  enamel  on  the  table  through  life.  The  incisors  are 
small  as  compared  with  the  other  teeth,  and  they  do  net 
contact  each  other  until  the  dog  is  more  than  a  year  old. 


40 


ANIMAL   DENTISTRY. 


O 

n 

c 


^ 


o     P 


O 
o 


ANIMAL   DENTISTRY. 


41 


The  canines  are  the  prominent  features  of  the  dog's  den- 
ture. They  are  large,  white  members  having  deep  implan- 
tations and  elongated  conical  crowns  curved  backwards, 
which  pass  each  other  in  a  manner  to  grasp  and  hold  firmly 


Fig.  30. 
Inferior   Denture   of  a   Dog.      (Cornevin    et   Lesbre.) 

any  object  caught  between  them.  The  molar  denture  is 
very  irregular,  as  is  also  each  individual  tooth.  The  first 
mferior  molar  of  dogs  is  properly  classified  as  a  temporary 
tooth  that  persists  in  the  mature  animal,  although  it  is  fre- 
quently referred  to  as  a  permanent  tooth  having  no  tern- 


42 


ANIMAL    DENTISTRY 


porary  predecessor.     The   first  and   second  inferior   molars 
have  small  conical   crowns,  slightly  cut  out  internally  and 


Fig.  31. 
Superior    Denture    of   an    Aged    Dog.      (Cornevin    et    Lesbre.) 

but  a  single  root.  The  third  and  fourth  present  on  the  crown 
one  large  cone  anteriorly  and  two  smaller  ones  posteriorly, 
and  each  fang  has  two  roots.     The  fifth  has  two  small  an- 


ANIMAI.  DENTISTRY.  43 

terior  cones,  three  small  posterior  ones  on  the  crown,  and 
three  roots.  The  sixth  inferior  has  two  roots  projecting 
backwards  and  presents  a  large  crown  with  a  number  of 
conical  projections  and  a  deep  infundibiilum.  The  seventh  is 
small  but  has  three  projections  on  the  table  and  two  roots. 

The  superior  molars  are  six  in  number  and  will  answer 
the  same  general  description  as  the  inferior  ones,  located 
behind  the  first,  but  their  crowns  are  wider  and  more  beveled 
from  within  outward. 


CHAPTER  II. 

EVOLUTION  OF  THE  TEETH. 

The  teeth  are  not  a  part  of  the  skeleton  and  never,  like 
other  juxtaposited  hard  tissues,  unite  to  each  other  or  to  the 
bones  that  surround  them.  They  originate  from  the  mucous 
membranes  of  the  mouth  and  develop  independently  of  the 
bones.  They  are  appendages  of  the  buccal  mucosa  precisely 
as  horn,  hair  and  hoof  are  appendages  of  the  skin. 

The  evolution  (growth)  of  the  teeth  and  their  subse- 
quent retrogression  (wear)  occurs  in  such  distinct  succes- 
sive stages  from  embryo  to  old  age  that  the  age  of  animals 
can  be  accurately  determined  at  any  period  of  life.  The 
stages  of  evolution  and  the  stages  of  retrogression,  however, 
vary  with  each  species — the  horse,  the  dog,  the  ox  and  the 
cat  each  showing  individual  characteristics.  The  stages  of 
evolution  are  distinct  in  all  species,  while  those  of  retro- 
gression are  only  apparent  in  the  horse,  the  ox,  the  sheep 
and  the  pig.  The  dog,  the  cat  and  man  show  no  visible 
distinct  stages  of  wear,  owing  to  the  difYerent  anatomical 
construction  of  the  teeth. 

Dental  evolution  naturally  divides  itself  into  three 
periods : 

1st.     The  embryonic  evolution. 

2nd.      Evolution  of  the  temporary  teeth. 

3rd.     Evolution  of  the  permanent  teeth. 

EMBRYONIC  EVOLUTION. 

In  the  embryo  of  the  domestic  mammal  tooth  formation 
begins  at  the  seventh  week  of  foetal  life.     The  dental  ap- 

44 


ANIMAL   DENTISTRY 


45 


paratus  at  that  time  is  represented  by  a  whitened  ridge  of 
mucous  membrane  extendmg  around  the  maxillary  margin. 
This  ridge  (gingival  cushion)  is  the  matrix  from  which  the 
teeth  develop.  At  the  earliest  period  it  consists  chiefly  of 
two  layers  of  epithelial  cells  and  basement  membrane  of 
connective  tissue.  The  outer  layer  consists  of  loosely  ar- 
ranged cells  while  the  deep  one  is  dense  and  lies  in  close 
relation  to  the  jaw,  being  only  divided  from  the  latter  by  the 
thin  connective  tissue  of  the  mucous  membrane. 

A i^ 

7   P 


•hr. 


-^ 


-t^-rt^i 


& 


Fig.  ,12. 
Section  Through  a  Part  of  a  Dental  Follicle.      (Cornevin  et  Lesbre.) 

1.  Crusta  petrosa. 

2.  External    enamel. 

3.  4,  S.     Internal  enamel. 

6.  Dentine. 

7.  Odontoblasts. 

8.  Pulp. 

The  following  changes  which  the  gingival  cushion  under- 
goes constitute  the  process  of  tooth  development :  The  first 
step  in  the  direction  of  tooth  formation  is  observed  at  about 


46 


ANIMAL   DENTISTRY. 


1. 
2. 
3. 
4. 
5. 


Fig.  33. 

Perpendicular  Section  Through  a  Dental  Papilla. 
Epithelium  of  the  gingival  cushion. 
Stalk  for  the  future  permanent  tooth. 
First  dentinal  formation. 
The  jaw  bone. 
The  alvoelar  periosteum. 


The  crescent-shaped  ring  represents  the  enamel  organ. 


ANIMAL   DENTISTRY.  47 

the  eighth  week  of  foetal  life,  when  the  deep  cellular  layer 
of  the  gingival  cushion  begins  to  grow  inward  into  the  sub- 
stance of  the  jaw,  which  at  that  period  is  represented  by- 
cartilage.  The  cartilaginous  jaw  at  the  same  time  grows 
upward  around  the  descending  epithelium  until  it  presents 
a  deep  trough-like  groove  which  the  gingival  cushion  now 
occupies.  The  outer  or  loose  layer  remains  without  and 
persists  through  life  as  the  gums,  while  the  deep  or  dense 
layer  pushes  deeper  and  deeper  into  the  jaw,  becomes  better 
organized  to  form  the  common  enamel  germ.  The  common 
enamel  germ  which  is  no  more  than  the  deep  epithelial  layer 
of  the  gingival  cushion,  is  continued  evenly  through  the 
whole  trough,  but  at  the  ninth  or  tenth  v/eek  of  foetal  life 
it  becomes  tumefied  at  regular  intervals  to  form  the  first 
real  representatives  of  the  future  teeth  Tthe  enamel  germs). 
As  the  enamel  germs  devlop  into  larger  bodies  the  sub- 
stance between  them  gradually  disappears,  leaving  only  a 
small  mound  for  each  temporary  tooth.  Simultaneously  the 
basement  layer  of  the  gingival  cushion  tumefies  beneath 
this  mound  and  forces  it  upwards  into  a  permanent  body 
(the  dental  papilla).  The  dental  papilla  consists,  therefore, 
of  a  body  of  connective  tissue,  capped  with  epithelium. 

At  the  third  month  of  foetal  life  the  epithelial  layer  un- 
dergoes petrification  to  form  the  future  enamel  organ.  The 
connective  tissue  calcifies  to  form  dentinal  substance,  while 
the  base  of  the  papilla  remains  unchanged  to  form  the  pulp. 
While  this  process  is  going  on  the  papilla  is  gradually  as- 
suming the  shape  and  form  of  a  tooth  crown,  the  first  di- 
vision of  a  tooth  to  form.  The  neck  and  fang  occur  by  the 
deposition  of  dentinal  substance  at  the  base  of  the  papilla. 
The  aperture  into  the  pulp  cavity  is  at  first  a  wide  one,  but 
soon  becomes  narrow  and  takes  its  place  at  the  end  of  the 
fang  as  an  apical  foramen,  the  opening  through  which  the 
vessels  and  nerves  enter  the  tooth.     In  the  case  of  the  molar 


48  ANIMAL   DENTISTRY. 

teeth  several  openings  are  formed,  one  for  each  root.  The 
cement  is  ossified  connective  tissue,  and  is  the  last  of  the 
three  hard  tissues  to  form.  It  develops  l^etween  the  perios- 
teum of  the  tooth  cavity  and  the  dental  substance  and  is 
influenced  in  its  evolution  throuj^h  life  by  both  these  ele- 
ments. 

During  these  evolutionary  changes  each  tooth  is  en- 
closed within  a  separate  sac  ordinarily  designated  as  a  den- 
tal follicle.  During  the  same  period  the  jaw  is  undergoing 
great  changes.  It  is  growing  upward  to  further  enclose  the 
follicles  within  itself,  and  is  gradually  separating  them  one 
from  another  l)y  the  formation  of  bony  partitions  (the  inter- 
dental cancellated  tissue)  until  each  tooth  occupies  a  deep 
individual  compartment — the  alveolar  cavity — which  the 
tooth  fills  completely  at  every  stage  of  its  evolution  and  ex- 
istence and  which  entirely  encloses  both  until  by  sheer 
force  of  its  expansion  it  forces  its  way  into  the  mouth  and 
takes  its  place  at  the  level  of  the  dental  arcade.  This  event 
marks  the  beginning  of  the  second  period  of  dental  evolu- 
tion. 

The  permanent  teeth  are  developed  much  in  the  same 
manner.  About  the  sixteenth  week  of  foetal  life  a  stalk  or 
neck  becomes  disconnected  from  the  common  enamel  germ 
and  takes  its  place  first  on  the  side,  and  secondly,  at  the  root 
of  the  temporary  tooth.  It  undergoes  the  same  steps  of  de- 
velopment, and  by  its  upward  growth  absorbs  the  fang  of 
the  temporary  tooth  until  only  a  mere  shell  remains.  The 
permanent  teeth  that  are  not  represented  by  temporary 
predecessors  are  formed  by  the  backward  extension  of  the 
common  enamel  germ.  The  first  permanent  tooth  of  this 
class — the  fourth  molar — has  its  origin  in  embryo,  while  the 
others  which  erupt  later  in  life  may  not  begin  to  form  until 
some  time  after  birth.  The  enamel  germ,  therefore,  is  not 
entirely  a  foetal  structure,  but  exists  until  the  last  tooth  is 


ANIMAL  DENTISTRY.  49 

set  on  its  way  toward  maturity.     (Thus  far  dental  evolution 
does  not  vary  materially  in  the  different  species). 

EVOLUTION  OF  THE  TEMPORARY  TEETH. 

This  period  of  dental  evolution  begins  when  the  milk 
teeth  make  their  first  appearance  on  the  buccal  surface,  and 
ends  when  they  are  entirely  replaced  by  their  permanent 
successors.  In  some  animals  the  temporary  teeth  erup-t  be- 
fore birth.  It  is,  however,  at  the  time  of  birth  or  within  a 
few  days  after  that  the  first  evidence  of  temporary  dentition 
appears  in  all  domestic  animals.  The  end  of  the  period 
varies  with  each  species.  In  the  horse  the  last  temporary 
teeth  disappear  at  four  and  a  half  years  of  age.  Thus  the 
period  in  the  horse  lasts  from  birth  to  four  and  a  half  years 
of  age,  in  the  ox  from  birth  to  four  and  a  half  years,  in  the 
sheep  from  birth  to  three  and  a  half  years,  in  the  dog  from 
birth  to  six  months,  and  in  the  pig  from  birth  to  three  years. 
In  all  the  domestic  animals  except  the  dog  the  temporary 
incisors  persist  longer  than  the  molars. 

THE  HORSE. 

The  central  incisors  erupt  before  birth  or,  in  some  in- 
stances, within  a  few  days  after.  They  are  large,  white 
teeth,  occupying  the  entire  incisor  arcade  and  contact  their 
opposing  teeth  by  their  anterior  borders  only.  The  pos- 
terior border  is  still  hidden  beneath  the  gums  and  only 
comes  to  the  level  of  the  anterior  border  after  three  months' 
wear,  at  which  time  they  present  the  typical  table  of  an 
herbivorous  incisor.  The  cup  is  deep  and  distinct,  and  in  its 
whole  appearance  cannot  be  readily  recognized  from  that  of 
a  permanent  incisor.  At  the  earliest  period  after  eruption 
two  influences  are  at  work  for  their  destruction — the  perma- 
nent tooth  is  gradually  encroaching  upon  its  fang  while  the 
crown  is  becoming  shorter  and  shorter  under  the  influence 


so 


ANIMAL    DENTISTRY. 


of  wear  until  at  the  a.£;c  of  two  aiul  a  half  years  there  remains 
only  a  loosened  shell. 

LATERAL  INCISORS. 

The  lateral  incisors  make  their  af)pcarance  at  from  four 

to  six  weeks,  t^ain  the  level  of  the  arcade  at  four  months, 

and  are  replaced  by  permanent  incisors  at  three  and  a  ha'f 

years, 

CORNER  INCISORS. 

The  comer  incisors  appear  on  the  buccal  surface  at  about 


Fig.  34. 
Temporary  Incisor  Teeth   of  a  Horse. 
A,  B,  C.     Labial  surface  of  central,  lateral  and  corner. 
D,  E,  F.     Lingual   surface  of  same. 

seven  months,  gain  the  level  of  the  arcade  at  ten  months 
and  are  shed  at  four  and  a  half  years. 

FIRST,  SECOND  AND  THIRD  MOLARS. 

These  teeth  appear  about  the  time  of  birth.  They  are 
large  organs  and  occupy  the  whole  maxillary  margin  behind 
the  interdental  space.  At  the  time  of  eruption  their  tables 
are  covered  with  enamel,  which  soon  wears  off  to  expose 
the  dentinal  tissue  and  cement.  Their  fangs  are  gradually 
lost  by  absorption  from  pressure  of  the  growing  permanent 
molars  beneath.  The  first  and  second  are  shed  at  two  and 
one-half  years  and  the  third  at  three  to  three  and  a  half, 
leaving  the  molar  arcades  free  from  temporary  teeth. 


ANIMAL  DENTISTRY. 


51 


CANINES. 

The  canine  teeth  are  frequently  referred  to  as  being  rep- 
resented in  youth  by  temporary  predecessors.  This  claim 
cannot  be  accepted  as  entirely  correct.  The  needle-like  ca- 
nines, occasionally  observed  in  three-year-old  colts,  must  be 
reo-arded  as  a  freak  of  perverted  dental  evolution  rather 
than  as  a  part  of  the  normal  economy. 


Fig.  35. 

Temporary  Incisors  of  the  Colt. 
Inferior  incisors  at  birth. 
Inferior  incisors  at  ten  weeks. 
Inferior  incisors  at  four  months. 


3- 

4- 
2. 
I.     Inferior  incisors  at  seven  months. 


THE  OX. 

Central  Incisors''' — Erupt  at  birth,  become  prominent  at 
one  month  and  shed  at  one  and  a  half  years  of  age. 

Lateral  Incisors — Erupt  at  birth,  gain  the  level  of  the 
arcade  at  one  month  and  shed  at  two  and  a  half  years. 


*Lower  jaw  only. 


52 


ANIMAL   DENTISTP.Y. 


Intermediate  Incisors — The  intermediates  erupt  at  two 
weeks,  gain  the  level  of  the  arcade  at  two  months  and  shed 
at  three  and  a  half  years. 

Comer  Incisors — The  corners  erupt  at  three  weeks  to  one 
month,  gain  the  level  of  the  arcade  at  three  months  and  shed 
at  four  and  a  half  years. 

First,  Second  and  Third  Molars — As  in  the  horse,  these 


Fig.  36. 
Temporary   Molar  Teeth   of  a  Horse. 

molars  erupt  at  birth.  The  first  is  cast  off  at  one  and  a  half 
years,  the  second  at  two  and  a  half  years  and  the  third  at 
three  and  a  half  years. 

THE  PIG. 
Central  Incisors — Erupt  at  three  to  four  months  and  arc 
shed  at  three  years. 


i   '"'A 


Fig.  ^7. 
Superior   and   Inferior   Molar   Arcades   of   tlie    Ilorsc   under   the   Age   of   10 

Montlis. 
A,  B.     Opening  for  the  4th  Molar. 

58 


54  ANIMAL  dp:ntistrv. 

Lateral  Incisors — Irrupt  at  fcnir  months  and  arc  shed  at 
three  years. 

Corner  Incisors — Irrupt  at  hirth  and  are  shed  at  six 
months. 

Canines — Erupt  at  birtli  and  are  slied  at  one  year  (The 
temporary  canines  of  the  pis:^  are  common  to  both  sexes,  hnt 
are  more  prominent  in  the  male). 

First  Molar — The  llrst  molar  of  the  lio,^;  has  no  temporary 
predecessor. 

Second  and  Third  Molars — Erupt  at  birth  and  arc  shed 
at  two  years. 

Fourth  Molar — Erupts  at  six  months  and  is  shed  at  two 

years. 

THE  DOG. 

Central  Incisors — Erupt  at  four  weeks  and  are  shed  at 
four  months. 

Lateral  Incisors — Erupt  at  four  weeks  and  are  shed  at 
four  months. 

Corner  Incisors — Erupt  at  four  weeks  and  are  shed  at 
five  months. 

(The  incisor  teeth  do  not  come  in  contact  with  one  an- 
other until  the  ag-e  of  fifteen  months). 

Canines — Erupt  at  four  weeks  and  are  shed  at  six  months. 
They  are  common  to  both  sexes. 

First  Molar — There  is  no  temporary  first  molar  in  the 
dog. 

Second,  third  and  fourth  molars  erupt  at  five  to  six  weeks 
and  shed  at  six  months.  The  fourth  may  l)e  delayed  until 
six  and  one-half  to  seven  months. 

At  the  age  of  seven  months  the  temporary  denture  of 
the  dog  is  entirely  replaced  by  its  permanent  successor. 


Fig.  38. 


Superior  Denture  of  a  2- Year-old  Hog,     (Cornevin  ct  Lesbre.) 


55 


56 


ANIMAL    DENTISTRY. 


THE  SHEEP. 

Central  Incisors — Erupt  (hiring;-  llic  I'lrst  month  after  birth 
and  are  shed  at  fifteen  to  eighteen  months. 

Lateral  Incisors — Erupt  during-  the   first    month,  a   few 


o 


bo 
< 


bfl 
O 


days  after  the  centrals,  and  are  shed  at  twenty  to  twenty-four 
months. 


ANIMAL   DENTISTRY. 


57 


Intermediate  Incisors — Erupt  during  the  second  to  the 
fourth  week,  a  few  days  after  the  laterals,  and  are  shed  at 
twenty-four  to  thirty-three  months. 

Comer  Incisors — Erupt  about  the  fifth  week  after  birth 
and  are  shed  at  four  to  four  and  a  half  years. 


First  Molar — Erui)ts  during-  the  first  month  and  is  shed 
at  one  and  a  half  years. 

Second  Molar — Erupts  with  the  first  molar  and  is  shed 
at  two  and  a  half  years. 

Third  Molar — I-'.rupts  with  the  first  and  second  and  is 
shed  at  three  and  a  half  years. 


58 


ANIMAL    DENTISTRY. 


EVOLUTION  OF  THE  PERMANENT  TEETH. 

The  ilcx'clopnK'nl  of  tlic  peniiancnl  tcctli  of  animals  ])e- 
g-ins  during'  llie  foetal  life.  During;-  this  period  tliey  are  rep- 
resented only  1;\-  a  stalk  or  neek  extendini^-  from  the  enamel 
germ  of  their  tem])orary  analogues,  located  first  on  the  side 


Fig.  41. 
A-Iolar   Denture  at   Birth. 

A.  Inferior  4th   molar. 

B.  Superior  4th  molar. 

and  afterwards  at  the  root.  At  the  time  of  birth  the  germ  of 
the  central  incisors  and  the  first,  second  and  third  molars 
are  already  prominently  formed  at  the  root  of  the  temporary 
teeth,  and  the  fourth  molar — the  first  permanent  tooth  to 
develop — consists  of  a  rounded  hypertrophy  of  the  common 
enamel  germ  located  just  posterior  to  the  third  temporary 
molar.     (  Fig.  41  A.  B.)     The  temporary  molars  occupy  the 


ANIMAL   DENTISTRY. 


59 


entire  jaw  behind  the  interdental  space  until  the  age  of  ten 
months.  In  the  herbivora  the  fourth  molar  forces  its  way 
to  the  surface  in  the  same  relative  position  that  the  sixth 
molar  occupies  in  the  mature  animal.  The  jaw  is  therefore 
always  filled  with  molars,  the  fourth,  fifth  and  sixth  forcing 
their  way  behind  their  successive  neighbors. 


Fig.  42. 
Molars  of  a  Horse  Approaching  5  to  6  Months. 

During  the  first  year  the  only  prominent  visible  event  in 
the  evolution  of  the  permanent  teeth  is  the  eruption  of  the 
fourth  molar.  The  invisible  events  occurring  in  the  germs 
located  at  the  roots  of  the  temporary  are,  however,  of  no 
less  importance.  They  are  developing  rapidly  into  teeth  of 
normal  shape  and  size,  gradually  transgressing  upon  and 
-shortening  by  absorption  the  fangs  of  the  temporary  teeth, 


60 


ANIMAL  DENTISTRY. 


molars  and  incisors  alike.  The  first,  second  and  third  mo- 
lars make  the  most  rapid  proi^Tess  (hirinsj;-  the  hrst  year,  pre- 
paratory to  their  sul)se(inent  ernption  one  to  two  years 
hence.  The  incisors  are  less  (level()i)ed.  the  centrals  are 
somewhat  prominent  preparatory  to  their  eruption  two  years 
hence,  but  the  lateral,  interiuediates — in  ruminants — and  the 
corners  are  merely  represented  by  an  undeveloped  tooth 
germ.     Such  is  the  condition  of  development  of  the  denture 


Fig.  43. 
Molars   of   a   Horse   Approaching    10   IMonths. 

of  an  herbivorous  animal  at  the  age  of  one  year  from  whence 
the  evolution  proper  l)eg"ins.     (See  Fig.  43.) 

THE   HORSE. 


Central  Incisor — Begins  to  develop  in  embryo,  assumes 
the  shape  of  a  tooth  during  the  first  year,  reaches  the  level 
of  the  alveolar  border  at  two  years,  expels  the  temporary 
shell  at  two  and  a  half  years  and  takes  its  place  at  the  nor- 
mal level  of  the  arcade  at  three  years  of  age. 

Lateral  Incisor — Begins  to  develop  during  the  first  six 


ANIMAL  DENTISTRY.  61 

months,  assumes  the  shape  of  a  tooth  during  the  second  year, 
reaches  the  alveolar  border  at  three  years,  expels  the  tem- 
porary shell  at  three  and  a  half  years  and  takes  its  place  at 
the  level  of  the  arcade  at  four  years. 

Comer  Incisor — Is  very  rudimentary  at  one  year,  begins 
to  develop  at  two  years,  assumes  the  shape  of  a  tooth  at 
three  years,  reaches  the  alveolar  border  at  four  years,  expels 
the  temporary  shell  at  four  and  a  half  years  and  takes  its 


Fig.  44. 
Molars  of  a  Horse  Approaching  the  Age  of  2  Years. 

place  at  the  level  of  the  arcade  at  five  to  five  and  a  half  years. 

Canines — Erupt  at  the  age  of  four  to  four  and  a  half 
years,  but  may  be  delayed  in  their  outward  course  by  the 
hardness  of  the  jaw.  Occasionally  their  growth,  especially 
of  the  superiors,  is  arrested  beneath  the  gums  until  the  sev- 
enth year  of  the  animal's  life.  The  inferior  canines  always 
erupt  slightly  in  advance  of  the  superior. 

First,  second  and  third  molars  begin  to  develop  in  the 
foetal  life  of  the  colt.     At  birth  they  arc  small,  rudimentary 


62 


ANIMAL  DENTISTRY. 


objects,  but  become  tooth-like  very  rapidly  during  the  first 
twelve  months,  at  w^hich  time  they  are  all  morphologically 
and  anatomically  similar.  During  the  ensuing  year  their 
growth  is  about  equal,  each  growing  to  the  level  of  the 
alveolar  border.  At  two  and  a  half  years  the  first  and  sec- 
ond expel  the  temporary  shell  and  become  concerned  ac- 
tively in  mastication  at  about  three  years  of  age.  The  third 
at  two  and  a  half  years  seems  to  be  mysteriously  retarded 
in  its  growth  as  if  blocked  in  its  outward  course  by  the 
unyielding  fourth  molar,  which  has  now  been  in  active  serv- 
ice for  the  past  one  and  a  half  years.  (See  osteoma  of  the 
maxilla.)  At  two  to  two  and  a  half  years  old  the  develop- 
ment of  the  third  molar  is  at  a  standstill,  until  the  age  of 
three  to  three  and  a  half  years,  when  it  finally  expels  its  shell 
and  then  grows  tardily  outward  to  the  level  of  the  arcade. 
It  is  not  unusual  to  find  this  molar  below  the  level  of  its 
neighbors  at  four  and  even  five  years  old. 

Fourth  Molar — The  fourth  molar  is  the  most  interesting 
of  the  horse's  teeth.  Its  development  begins  during  the  last 
months  of  foetal  life.  At  birth  it  consists  of  a  small,  rounded 
mass  of  rudimentary  tooth  substance,  developing  from  a 
backward  projection  of  the  common  enamel  germ,  and  lo- 
cated in  close  contiguity  to  the  fang  of  the  third  temporary 
molar.  During  the  first  ten  months  after  birth  it  grows 
very  rapidly  into  a  shapely  tooth  and  points  to  the  surface 
at  about  the  end  of  the  tenth  month.  At  twelve  months  it 
is  already  actively  concerned  in  mastication,  although  it  is 
morphologically  defective,  assuming  its  maximum  stability 
only  during  the  next  two  years. 

Fifth  Molar — The  common  enamel  germ  at  the  age  of 
six  months,  after  having  formed  the  fourth  molar  projects 
backward  to  form  the  fifth  molar.  At  one  year  old  the  for- 
mation is  almost  perfect,  at  one  and  a  half  years  it  erupts, 


ANIMAL  DENTISTRY. 


63 


and  at  two  and  a  half  years  it  is  found  on  a  level  with  the 
fourth. 

Sixth  Molar — The  sixth  molar  is  the  last  of  the  molars 
to  erupt,  which  event  occurs  at  any  time  between  four  and 
five  years  of  age.  Its  formation,  like  that  of  the  other  per- 
manent molars,  having  no  temporary  predecessors,  depends 
upon  the  backward  growth  of  the  common  enamel  germ. 
The  first  evidence  of  this  molar  is  seen  at  two  to  two  and 


Fig.   45. 
Molar   Denture   of   the   Ox   at    10   Months. 

a  half  years  in  the  form  of  a  rounded  mass  similar  to  that 
of  the  fourth  and  fifth.  At  this  age  the  jaw  is  more  un- 
yielding and  its  eruption  may  be  delayed  by  the  resistance 
offered  therefrom. 

RUMINANTS. 

Central  Incisor — Reaches   the   alveolar   margin    at    one 
year  and  erupts  at  one  and  a  half  years. 


64  ANIMAL  DENTISTRY. 

Lateral  Incisor — Reaches  the  alveolar  margin  at  two 
years  and  erupts  at  two  and  a  half  years. 

Intermediate  Incisor— Reaches  the  alveolar  margin  at 
three  years  and  erupts  at  three  and  a  half  years. 

Corner  Incisor — Reaches  the  alveolar  margin  at  four 
years  and  erupts  at  four  and  a  half  to  five  years. 

First  Molar — Reaches  the  alveolar  margin  at  one  year, 
expels  the  temporary  shell  at  one  and  a  half  years  and  be- 
comes concerned  in  mastication  soon  after. 

Second  Molar — Reaches  the  alveolar  margin  at  two 
years,  expels  the  temporary  shell  at  two  and  a  half  years 
and  gains  the  level  of  the  first  molar  a  month  or  two  later. 

Third  Molar — Reaches  the  level  of  the  alveolar  margin 
at  three  years,  expels  the  temporary  shell  at  three  and  a 
half  years  and  gains  the  table  level  at  about  four  years. 

Fourth  Molar — Erupts  at  nine  months  and  becomes  con- 
cerned in  mastication  at  ten  to  eleven  months. 

Fifth  Molar — Erupts  at  two  and  a  half  years  and  gains 
the  table  level  several  months  later. 

Sixth  Molar — Erupts  between  the  ages  of  four  and  five 
years.  As  in  the  horse,  its  outward  progress  is  hindered  by 
the  hardness  of  the  jaws  at  that  age. 

CARNIVORA. 

Central  Incisor — Erupts  at  three  to  four  months. 

Lateral  Incisor — Erupts  at  three  to  four  months. 

Corner  Incisor — Erupts  at  five  to  five  and  a  half  months. 
Canines — Erupt  at  five  to  six  months,  common  to  both 
sexes. 

First  Molar — Erupts  at  three  months,  and  has  no  tem- 
porary predecessor. 

Second  Molar — Erupts  at  five  to  six  months. 

Third  Molar — Erupts  at  five  to  six  months. 

Fourth  Molar — Erupts  at  five  to  six  months. 

Fifth  Molar — Erupts  at  four  to  five  months. 


ANIMAL  DENTISTRY.  55 

Sixth  Molar — Erupts  at  five  to  six  months. 
Seventh  Molar — Erupts  at  seven  months. 

OMNIVORA. 

Central  Incisor — Erupts  at  two  and  a  half  years. 

Lateral  Incisor — Erupts  at  three  years. 

Corner  Incisor — Erupts  at  six  months. 

Canine — Erupts  at  one  year  and  is  common  to  both  sexes. 

First  Molar — Erupts  at  birth  and  is  a  permanent  tooth. 

Second  Molar — Erupts  at  tw^o  years. 

Third  Molar — Erupts  at  two  to  two  and  a  half  years 

Fourth  Molar — Erupts  at  six  months. 

Fifth  Molar — Erupts  at  one  year. 

Sixth  Molar — Erupts  at  one  and  a  half  to  two  years. 

Seventh  Molar — Erupts  at  three  years. 

NUMBER  OF  PERMANENT  TEETH. 

Incisors.     Canines.     Molars.  Total. 

Horse    12  4  24  40 

Mare    12  o  24  36 

Ox    8  o  24  32 

Pig    12  4  28  44 

Dog  12  4  26  42 

Cat   12  4  14  30 

Rabbit    6  o  22  28 

NUMBER  OF  TEMPORARY  TEETH. 

Incisors.     Canines.     Molars.  Total. 

Horse    12  o  12  24 

Ox   8  o  12  20 

Pig    12  4  12  28 

Dog   12  4  24  30 

Cat   12  4  10  26 

Rabbit    8  o  24  32 


o 


J 


66  ANLMAlv  nl-:\TISTRV. 


r^ORMULAE   OF  THE  TEMPORARY   AND   PERMA- 
NENT DENTURES  OF  DOMESTIC  ANIMALS. 

HORSE. 

Temporary. 

3 3                     o o  3... 

Incisors: —                    Canines: —  ]\Iolars: — 

3 3                     o o  3... 

Permanent. 

3 3  I I  6 6 

Incisors: —  Canines: —  Molars: — 

3 3  I I  6 6 


OX. 

Temporary. 

4 4  o o  3 3 

Incisors: —  Canines: —  Molars: — 

o o  o o  3 3 

Permanent. 

4 4  o o  6 6 

Incisors: —                     Canines: —  Molars: — 

o o  o o  6 6 

DOG. 

Temporary. 

3 3  1 I  3 3 

Incisors: —  Canines: —  Molars: — 

3 3  I I  3 3 


ANIMAL  DENTISTRY.  67 

Permanent. 

3 3  I I  ^ 6 

Incisors: —  Canines: —  Molars: — 

3 3  I I  7 7 

CAT. 

Temporary. 

3 3  I I  •        3 3 

Incisors: —  Canines: —  Molars: — 

3 3  I I  2 2 

Permanent. 

3 3  I I  4 4 

Incisors: —  Canines: —  Molars: — 

3 3  I I  3 3 

PIG. 

Temporary. 

3 3  I I  3 3 

Incisors  : —  Canines  : —  Molars  : — 

3------3  I I  3 3 

Permanent. 

3 3  I I  7 7 

Incisors: —  Canines: —  Molars: — 

3 3  I I  7 7 


CHAPTER  III 

RETROGRESSION  OF  THE  TEMPORARY  TEETH. 

"J'he  temporary  teeth  attain  their  i^-reatest  capacity  and 
length  at  the  time  of  eruption,  after  which  event  they  at  once 
begin  to  retrogress  under  the  infUiences  of  pressure  ab- 
sorption at  the  root  and  of  wear  from  mastication  at  the 
table  extremity,  until  only  a  shell  remains  to  be  expelled 
into  the  mouth.  The  first  event  of  this  character  (shed- 
ding) occurs  to  the  first  and  second  molars  at  two  and  a 
half  years,  and  the  last  to  the  corner  incisors  at  four  and  a 
half  years,  after  which  time  the  denture  is  entirely  free 
from  temporary  teeth.  The  order  of  shedding  of  the  tem- 
porary teeth  in  solipeds  is  as  follows: 

(i)  Two  and  a  half  years,  the  first  and  second  molars 
and  the  central  incisors. 

(2)  Three  to  three  and  a  half  years,  the  third  molars  and 
the  lateral  incisors. 

(3)  Four  and  a  half  years,  the  corner  incisors. 

This  order  may  1)e  made  to  apply  to  all  ruminants  and 
solipeds.  In  the  carnivora  the  destruction  of  the  temporary 
denture  is  remarkably  rapid,  as  at  the  age  of  seven  months 
no  temporary  teeth  remain. 

RETROGRESSION  OF  THE  PERMANENT  TEETH. 

The  retrogression  of  the  permanent  teeth  is  the  most  im- 
portant feature  of  dentistry  of  animals.  It  includes  the  wear 
and  eventual  destruction  of  the  teeth.  The  teeth  of  solipeds 
and  ruminants  attain  their  maximum  length  and  volume 
the  second  year  after  eruption.     During  the  first  year  they 

68 


ANIMAL  DENTISTRY. 


69 


gain  in  lenj^th  and  ^•olume  by  expansion  of  the  fang,  but 
lose  slightly  by  wear.  The  growth,  however,  exceeds  the 
wear  during  the  first  year.  During  the  second  year  the  wear 
and  growth  are  about  equal.  The  greatest  length  of  the 
teeth  is  therefore  attained  during  the  second  twelve  morAhs 
of  their  existence  within  the  mouth.     During  the  succeed- 


FlG.  46. 
The  Destruction  of  a  Temporary  Tooth  by  the  Permanent. 

A.  Temporary  shell. 

B.  Permanent  tooth. 

ing  years  the  teeth  do  not  grow,  but  instead  undergo  a 
gradual  and  regular  process  of  destruction  under  two  in- 
fluences : 

(i)  Wear  from  mastication,  which  slowly  shortens  th? 
length  of  the  tooth. 

(2)  Receding  of  the  alveolar  margin,  which  gradually 
shortens  the  depth  of  the  alveolar  cavity. 

In  the  herbivorous  animals  both  of  these  influences  are 


70  ANIM.  L   DENTISTRY. 

a\  AA'Oik  t\>  .1  reiiiarkable  dei^rcc,  while  in  the  carnivora  and 
oi  inivora  inly  the  second  inlliience  is  concerned  in  the  de- 
structive p"ocess.  In  the  lierbivora  the  len.^'h  of  the  teeth 
varies  from  the  lonu:,  three  or  fonr-inch  tootl-  of  the  young 
subject,  to  the  short,  half-inch  toot!-  of  extreme  old  age 
(from  the  wear  of  mastication),  while  the  alveolar  cavity 
varies  from  the  exceedingly  deep  excavation  of  youth  to 
the  shallow,  flattened  cavity  of  old  age.  The  diminution  in 
the  depth  of  the  alveolar  cavity  occurs  in  all  the  animals,  and 
is  solely  responsible  for  senile  self-extraction  in  the  animals 
having  simple  teeth.  In  the  animals  having  simple  teeth  the 
table  retains  its  enamel  covering  through  life,  and  the  tooth 
does  net  diminish  in  length  from  wear. 

I.  Wear  from  mastication. — When  the  teeth  of  the  ru- 
minant and  soliped  first  enter  into  the  process  of  mastica- 
tion they  are  covered  w^ith  enamel  over  the  grinding  sur- 
face. The  enamel  in  addition  dips  deeply  into  the  body  of 
the  tooth  around  the  infundibula.  As  soon  as  wear  begins 
the  surface  enamel  of  the  table  at  once  wears  off,  exposing 
the  dentine  and  leaving  only  the  edges  of  the  enamel  organ 
on  the  grinding  surface.  The  dentine,  ordinarily  a  sensitive 
substance,  becomes  hard  and  insensitive  along  the  table 
surface,  by  the  deposit  of  dentinal  cells  within  its  tubules. 
The  area  of  insensitiveness  extends  throughout  the  entire 
table  and  to  the  depth  of  one  to  two  millimeters  during  the 
first  year  of  wear,  but  in  the  subsequent  three  or  four  years 
it  descends  to  the  depth  of  one  centimeter  or  even  more.  At 
the  age  of  ten  to  twelve  years  it  has  descended  to  more  than 
one-third  of  the  entire  tooth  in  the  molars,  and  to  the  depth 
of  about  two  centimeters  in  the  incisors.  When  the  animal 
has  passed  the  age  of  eighteen  the  tooth  is  practically  a  dead 
organ  so  far  as  the  sensibility  of  the  dentine  is  concerned. 
That  the  stimulus  to  the  proliferation  of  dentinal  cells  (os-. 
teo-dentine)  is  wear  is  demonstrated  in  the  fact  that  teeth 


ANIMAL  DENTISTRY. 


71 


that  do  not  contact  opposing  teeth   (e.  g.,  brachygnathism) 
are  sensitive  to  the  very  tips. 

During  youth  and  through  the  prime  of  Hfe  the  active 
tooth  wears  at  the  rate  of  about  two  milHmeters  each  year. 
In  the  asred  animal  the  loss  is  slower.     In  the  case  of  the 


^5  yrs. 


^8yr5. 


^30yrs. 


Fig.  47. 

An  Illustration  of  the  Change  in  Shape  of  the  Incisor  Tables  as  a  Result  of 

Wear,  from  6  Years  to  30  Years. 

visible  teeth  (the  incisors)  the  wear  brings  to  the  surface 
of  the  table  a  constantly  changing  picture,  by  exposing  to 
view  the  different  consecutive  parts  of  the  tooth,  from  the 
flattened  table  of  youth  to  the  triangular  table  of  old  age. 
The  most  striking  change  in  the  teeth  from  wear  occurs 


72  ANIMAL  DENTISTRY. 

to  the  incisor  tcclh,  especially  the  inferiors,  which  furnish 
the  best  evidence  of  the  age  after  the  fifth  year.  First,  by 
changes  in  the  infundihulum  and  then  l)y  change  in  the 
shape  of  the  table  surface.  The  infundibuluni  of  the  tooth  '\s 
produced  by  the  infolding  of  the  enamel  into  the  body  of 
the  tooth  to  a  depth  of  one  and  a  half  to  two  and  a  half 
centimeters.  The  1)Ottom  of  the  cavity  thus  formed  is  filled 
with  crusta  petrosa,  but  the  outer  end  is  empty  and  consti- 
tutes the  cup.  A\hich  becomes  blackened  l)y  the  chemical 
action  of  foods  and  saliva.  The  infundibula  of  the  incisors 
are  shaped  like  a  flattened  cone  with  the  apex  inward  and 
the  elliptical  opening  outward.  AVhen  the  tooth  is  Imt  a 
virgin,  the  cup,  made  more  apparent  by  its  dark  color,  pre- 
sents an  elliptical  opening  at  the  table  surface,  but  as  the 
crown  w^ears  away  it  loecomes  shorter  and  more  rounded 
and  disappears  entirely  when  the  crown  has  worn  as  far 
as  the  crusta  petrosa  that  fills  the  bottom  of  the  infundibula. 
Thereafter  the  infundil)ula  are  not  dark  but  are  recognized 
by  their  surrounding  enamel,  at  first  still  elliptical,  but  final- 
ly becoming  small  circular  rings  located  w^ell  toward  the 
posterior  border  of  the  tables.  In  the  study  of  dental  wear 
the  cup  must  not  be  mistaken  for  the  infundibuluni,  as  "cup" 
refers  onl}^  to  the  unfilled  portion  of  the  infundihulum.  The 
cups  of  the  incisor  teeth  disappear  three  years  after  erup- 
tion, and  the  infundibuluni  about  ten  years  to  fifteen  years 
after. 

The  molar  teeth  have  two  infundibula  extending  deeply 
into  the  fang.  They  are  entirely  filled  with  crusta  petrosa 
and  would  entirely  escape  notice  but  for  the  presence  of 
a  small  dark  spot  in  the  center. 

In  shape  the  tables  change  even  more  than  in  their 
infundibula.  In  the  young  tooth  the  table  is  flattened  from 
before  backward,  but  as  the  crowns  wear  away  the  other 
parts  of  the  tooth  come  to  the  surface.     The  table  becomes 


ANIMAL  DENTISTRY.  73 

first  triangular,  then  round  and  finally  in  ex\  "eme  age  flat- 
tened from  side  to  side.  The  triangular  shape  makes  its  ap- 
pearance almost  as  soon  as  the  cups  disappear  in  the  central 
and  lateral  incisors,  while  the  corners  maintain  their  ob- 
long shape  until  after  the  age  of  twelve,  and  even  never 
become  as  distinctly  triangular  as  the  former.     (See  Fig.  47.) 

2.  Receding  of  the  alveolar  margin  is  more  prominent 
in  the  herbivora  than  in  the  other  species,  although  it  con- 
stitutes a  feature  of  dental  retrogression  in  all  animals. 
Through  its  influence  the  teeth  lose  their  implantation  by 
gradual  stages  until  in  extreme  old  age  they  are  held  in 
position  only  by  the  gums  and  small  pits  in  the  jaw,  which 
retain  the  remaining  roots. 

In  the  incisor  arcades  the  alveolar  margin  recedes  much 
faster  than  the  teeth  wear  at  the  table,  which  circumstance 
results  in  the  elongation  of  the  crowns  as  the  animal  be- 
comes older.  In  rare  cases  the  reverse  occurs  and  the 
crowns  become  shorter  with  age,  but  this  incident  results 
only  when  the  teeth  are  defective  in  quality.  The  long 
crowns  of  the  incisor  teeth  of  old .  horses  due  to  the  re- 
ceding jaw,  is  responsible  for  the  general  impression  that 
the  teeth  grow  in  length  and  that  they  are  longer  in  old 
than  in  young  horses. 

The  receding  process  is  also  responsible  for  the  gradual 
change  in  the  inclination  (angle)  of  the  incisor  teeth.  The 
angle  formed  by  the  incisor  teeth  at  the  contact  point  is 
ol)tuse  in  the  young,  but  changes  gradually  into  a  very  acute 
one  in  the  aged  animal.  This  change  is  the  result  of  the 
great  curvature  in  the  incisor  tooth,  which  in  tlie  young 
animal  is  implanted  into  a  deep  cur\'ed  cavity.  •  As  the 
tooth  wears  the  part  projecting  forwards  becomes  exposed 
and  the  increased  inclination  results.  The  incisor  teeth,  like 
all  teeth  of  herbivora,  are  longest  in  the  young  animal,  but 


74  ANIMAL  IJENTISTRV. 

have  a  longer  exposed  portion  (crown)  in  the  aged  subject, 
owing  to  the  receding  of  the  alverlar  margin. 

A  SUMMARY  OF  DENTAL  EVOLUTION  AND  RET- 
ROGRESSION APPLIED  TO  THE  DE- 
TERMINATION OF  AGE. 

The  a^-c  of  tlic  liorsc  is  (letcnniiicd  1)\'  the  examination 
of  the  incisor  teeth,  and  in  certain  instances  tlie  molars,  as 
follows : 

(i)      I'^-om  birth  to  one  year  by  the  evolution  of  th2 
temporary  incisors. 

(2)  From  one  year  to  two  and  a  half  years  by  the 

eruption  of  the  fourth  and  fifth  molars  and 
the  evolution   of  the  temporary  incisors. 

(3)  From  two  and  one-half  years  to  five  years  by 

the  retrogression  of  the  temporary  incisors, 
the  evolution  of  the  canines  and  the  evolu- 
tion of  the  sixth  molar. 

(4)  From  five  and  a  half  years  to  nine  years  l;y  tlie 

retrogression  of  the  infundil)u\a  of  the  in- 
ferior incisors. 

(5)  From  nine  years  to  old  age  by: 

(i)      Changes  in  the  shape  of  the  tables  of  the  in- 
ferior incisors. 

(2)  Changes  in  the  anterior  face  of  the  superior 

incisor  arcades. 

(3)  Changes  in  the  inchnation  of  the  incisor  ar- 

cades. 

(4)  Changes  in  the  crown  t^f  the  canines. 

(5)  Changes  in  the  molars. 

FROM  BIRTH  TO  ONE  YEAR. 

The  colt  at  birth,  or  within  a  day  or  two  after,  has  four 
incisor  teeth — the   superior  and   inferior  nippers,   and   thrc^ 


ANIMAL   DENTISTRY.  75 

molars  in  each  arcade,  the  first  second,  and  third.  The 
crowns  of  the  incisors  are  short  and  contact  only  at  the 
anterior  margin.  The  infundibnla  are  wide,  elliptical  and 
deep,  and  their  posterior  boundaries  are  buried  within  the 
gums.  At  one  month  the  posterior  edges  of  the  infundibula 
are  exposed  and  the  lateral  incisors  are  breaking  through 
the  gums.  Two  weeks  later  their  crowns  answer  the  same 
description  as  the  centrals  at  birth.  During  the  next  eight 
or  nine  months  there  is  no  great  change  in  the  arcades  ex- 
cept the  elongation  of  the  crowns,  which  resemble  a  cone 
broken  off  at  its  apex.     The  tenth  month  is  marked  by  the 

f  ■■ 


Fig.  47a. 
Inferior  Incisors  at  Birth, 

eruption  of  the   corner  incisors  and  the   fourth  permanent 
molars. 

FROM  ONE  TO  TWO  AND  A  HALF  YEARS. 

The  absence  of  any  prominent  event  during  this  period 
makes  the  determination  of  age  rather  difficult.  The  incisor 
teeth  become  large  and  prominent  in  all  the  features  of 
teeth,  and  are  not  easily  recognized  from  permanent  teeth. 
If  unassisted  by  the  colt-appearance  of  the  subject  the  mouth 
during  the  last  part  of  this  period  is  readily  mistaken  for  a 
full  mouth  of  permanent  incisors.  When  any  doubt  ex- 
ists the  examination  of  the  molars  will  reveal  the  presence 
of  but  four  teeth  in  each  arcade.  At  the  age  of  two  to  two 
and  a  half  years  tlie  fifth  molar  will  be  found  l^reaking 
through  the  gums.     The  incisors  are  white,  have  a  some- 


7G 


ANIMAL   DENTISTRY 


Figs.  48  and  49. 

Anterior   View   of  the   Incisor    Denture   at    12   Months. 

Incisors   (Table  View)   at   12  Months. 


ANIMAL   DENTISTRY. 


77 


Fig.  50. 
Incisor   Denture  at   15  Month.s    (Table  View) 


yj 


ANIMAL  DENTISTRY. 


Fig.  51. 
Incisor  Denture  of  a  Colt  at  18  Months   (Table  View). 


ANIMAL  DENTiSl  l<  V 


79 


Fig.  52. 
Incisor  Denture  at  2  Years    (Tabic  View). 


80 


ANIMAL   I)KN'1MS'IM<V. 


\\  hat  ])roniincnt  neck  and  arc  separated  w  illi  i^unis  shajjcd  as 
an  inverted  cone.  The  crowns  do  niit  contact  one  another 
throughont  their  entire  length,  as  in  llie  liorse  five  and  a 
half  to  six  years  old,  for  wliich  tlie  two-year-old  nii_i;ht  be 
mistaken.  'Jdie  absence  of  canines  (in  the  male)  will  also 
assist  in  makinj;-  the  differentiation.  "Jdie  confusion  is  most 
likely  to  occur  in  the  examination  of  a  thoroughbred  or  trot- 
ter with  a  well  developed  muscular  system,  and  the  habits  of 
an  older  horse  from  training. 

FROM  TWO  AND  A  HALF  TO  FIVE  YEARS. 

The  determination  of  age  during  this  period  is  more 
simple  and  more  certain  than  at  any  other  period  of  the 
horse's  life,  owing  to  the  three  successive  prominent  events 
occurring  during  this  period.  At  two  and  a  half  years  the 
central  temporary  incisors  are  readily  recognized  by  being 
loose  preparatory  to  shedding.  At  three  years  old  the}'  are 
cast  off  and  the  permanent  successors,  broad  and  shiny,  are 
seen  protruding  l)eneath,  leaving  an  interrupted  surface  in 
the  arcade.  At  three  and  a  half  to  four  years  the  laterals 
undergo  the  same  transformation,  and  at  four  and  a  half  to 
five,  the  corners.  The  five-year-old  mouth  is  recognized  by 
the  deep,  ol)long  infundilmla  of  the  centrals  and  laterals 
and  the  undeveloped  condition  of  the  corners.  The  latter 
are  bluish-white,  have  a  short  crown  and  do  not  contact  their 
opponents.  'Jlie  posterior  edge  of  the  table  is  still  buried 
within  the  gums.  The  canines  are  already  visi1)le  in  botli 
the  jaws,  but  especially  in  the  inferior,  and  the  molar  arcades 
are  completed.  At  two  and  a  half  years  the  first  and  sec- 
ond molars  cast  off  the  temporary  shells,  at  three  the  third 
molar  casts  off  its  predecessor,  and  at  four  to  four  and  a 
half  the  sixth  molar  erupts,  leaving  at  the  end  of  this  period 
a  full  mouth  of  permanent  teeth. 


ANIMAL  DENTISTRY. 


81 


Fic.  53- 
Incisor  Denture  Approaching  2^2.  Years   (Table  View). 


83 


ANIMAL  DENTISTRY. 


Fig.  54. 
Incisor  Denture  at  2^/2  Years    (Table  View). 


ANIMAL  DENTISTRY. 


83 


Fig.  55. 
Incisor  Denture  at  .1  Years   CTable  View). 


84 


ANIMAL   DENTISTRY. 


Fig.  56. 
^ncisor  Denture  at  3  Years    (Anterior  View; 


ANIMAL  DENTISTRY. 


85 


Fig.  57. 
Incisor  Denture  at  31^  Years   (Table  View). 


86 


ANIMAL  DENTISTRY, 


Fig.  58. 
Incisor  Denture  nt  4  Years   (Table  View). 


ANIMAL  DENTISTRY. 


87 


Fig.  59. 
Incisor  Denture  at  4  Years    (Anterior  View). 


88 


ANIMAL  DENTISTRY. 


Fig.  6o. 
Incisor  and  Canine  Dentures  at  4].  2  Years  (Table  View). 


ANIMAL  DENTISTRY.  gg 

FROM  FIVE  TO  EIGHT  YEARS. 

The  age  during  this  period  is  determined  by  changes  in 
the  infundibula  of  the  inferior  incisors,  the  cups  of  which 
disappear  in  regular  succession,  beginning  with  the  centrals. 
In  some  instances  a  small  round  spot  remains  for  several 
years  in  the  center  of  the  infundibulum,  but  this  event  must 
be  regarded  as  equivalent  to  the  disappearance.  The  disap- 
pearance of  the  blackened  cup  is  marked  by  the  appearance 
of  the  crusta  petrosa  filling  the  bottom  of  the  infundibulum. 
At  six  years  old  the  central  cup  disappears,  at  seven  the 
lateral  cup,  and  at  eight  the  corner  one  has  become  shallow 
and  rounded.  The  cup  of  the  corner  inferior  incisor  is  more 
persistent  than  that  of  the  centrals  and  laterals,  and  may 
remain  quite  prominent  even  at  the  age  of  ten  to  eleven 
years.  Its  change  in  shape  from  elliptical  to  round  is  equal- 
ly valuable  in  the  determination  of  the  age  at  that  period. 

FROM  NINE  YEARS  TO  OLD  AGE. 

After  the  age  of  nine  years  the  retrogressive  changes 
continue  incessantly,  but  without  any  prominent  event  to 
mark  the  exact  age.  The  age  of  the  horse  is  henceforth 
only  estimated. 

Nine  years — The  age  of  nine  years  is  easily  determined 
by  the  appearance  of  the  crusta  petrosa  groove  at  the  gingi- 
val margin  of  the  superior  corner  incisor  and  the  slight 
downward  curvature  of  the  gums  at  that  point.  The  infun- 
dibula of  the  inferior  incisors  are  nearer  to  the  posterior  bor- 
der of  the  tables  of  the  centrals,  which  are  now  quite 
triangular.  The  inferior  corner  incisors  are  still  oblong, 
present  a  rounded  black  cup  and  are  beginning  to  show  the 
first  sign  of  increased  inclination  of  the  incisor  arcades.  The 
anterior  surfaces  of  the  teeth  are  becoming  yellow. 


qo 


AMMAL   DENTIS'i-pY 


Fig.  6i. 
Incisor  Denture   Approaching  5   Years    (Table  View). 


ANIMAL  DENTISTRY. 


91 


Fig.  62. 
Incisor  Denture  at  5  Years   (Tabic  View). 


92 


ANIMAL  DENTISTRY. 


Fig.  63. 
Incisor  Denture  at  5^  Years  (Table  View). 


ANIMAL   DENTISTRY. 


93 


Fig.  64. 
Incisor  Denture  at  6  Years  (Table  View). 


^ 


ANIMAL    I)1:NTI8TKV 


Fig.  65. 
Incisor  Denture  at  6  Years    (Anterior  View). 


ANIMAL  DENTISTRY. 


95 


Fig.  65 a. 
Incisor  Denture  at  6  Years   (Lateral  View),  with  Dark  Lines  Showing  In- 
clination 


96 


ANIMAL   DENTISTRY. 


Fig.  66. 
Incisor  Denture  at  6^/2  Years  (Table  View). 


ANIMAL  DENTISTRY. 


97 


Fig.  66a. 
Incisor  Denture  of  a  Mare  at  6}i  Years  (Table  View). 


98 


ANIMAL  DENTISTRY. 


Fig.  67. 
Incisor  Denture  at  7  Years    CTable  View). 


ANIMAL    DENTISTRY. 


99 


Fig.  68. 
Inci.sor   Denture   at  7   Years,    Dark   Lines    Showing   Inclination. 


100 


ANIMAL   DENTISTRY. 


Fig.  69. 
Incisor  Denture  of  a  Mare  at  7  Years    (Table  View). 


ANIMAL  DENTISTRY. 


101 


Fig.  70. 
Incisor  Denture  at  8  Years   CTaWe  View). 


102 


ANIMAL    DENTISTRY. 


Fig.  71. 
Incisor  and  Canine  Dentures  at  9  Years   (Table  View). 


ANIMAL    DENTISTRY. 


103 


Fig.  72. 
Incisor  Denture  at  9  Years,  with   Dark  Lines   Showing  the  Inclination. 


lU4 


ANIMAL    DENTISTRY 


Fig.  ^2,. 
■Incisor  Denture  of  a  Mare  at  9  Years  (Table  View). 


ANIMAL   DENTISTRY.  i05 

Ten  to  twelve  years — The  inferior  centrals  and  laterals 
are  more  triangular,  the  cups  of  the  inferior  corners  are 
disappearing  entirely,  the  enamel  around  the  infundibula 
of  the  centrals  and  laterals  is  changing  from  oblong  to  round, 
the  crusta  petrosa  groove  on  the  superior  corners  is  two 
to  three  millimeters  long  and  is  appearing  on  the  laterals 
and  centrals,  and  finally  the  length  of  the  crowns  of  the 
superior  incisors  is  markedly  increased.  The  crowns  of  the 
canines  are  large  and  are  becoming  rounded  at  the  gingival 
margin.  The  inclination  of  the  incisor  arcades  is  now  a 
marked  feature  of  the  mouth  and  is  recognized  by  a  mere 
glance  at  the  lateral  aspect  of  the  arcades.    (Figs.  74,  75,  "^6.^ 

Thirteen  to  fifteen  years — The  crusta  petrosa  groove  on 
the  superior  corner  incisor  is  nearing  the  middle  of  the 
crown,  the  tables  are  markedly  triangular,  the  crowns  of 
the  superior  incisors  are  becoming  widely  separated  from 
the  gums,  and  are  becoming  narrow  near  the  gingival  mar- 
gin, the  infundibula  of  the  central  and  lateral  inferior  in- 
cisors are  now  but  small  circles  of  enamel — the  enamel 
island — projecting  above  the  level  of  the  dentine  and  located 
well  toward  the  posterior  aspect  of  the  table,  and  the  gingi- 
val margin  of  the  superior  central  incisors  is  much  lower 
than  that  of  the  laterals.  The  crowns  of  the  canines  are 
round  at  the  gingival  margin      (Fig.  yj.^ 

Sixteen  to  twenty  years — The  inclination  of  the  incisor 
arcades  is  so  pronounced  that  the  inferior  incisors  pro- 
ject forward  almost  on  a  straight  line  with  the  jaw,  the 
superior  corner  incisor  is  grooved  almost  to  the  contact 
border,  the  crusta  petrosa  grooves  extend  well  downward 
over  the  crowns  of  all  the  incisors,  the  crown  of  the  cen- 
trals is  shorter  than  that  of  the  laterals,  the  infundibula  have 
either  disappeared  entirely  or  exist  only  in  the  form  of 
small  projections  of  enamel  near  the  posterior  border  of  the 
tables  of  the  inferior  incisors,  the  crowns  of  all  the  superior 


106 


AM\rAT.    ])KXTISTRY. 


Fig.  74. 
Incisor  and  Canine  Dentures  at  10  Years  (Table  View). 


ANIMAL    DENTISTRY. 


107 


Fig.  75. 
Incisor  Denture  at  12  Vears  (Table  View). 


108 


ANIMAL   DENTISTRV. 


Fic.  "](>. 

Incisor  Denture  Between  the  Ages  of  lo  and  12,  Inclusive,  with  Dark  Lines 

Showinsr  the  Inclination. 


ANIMAL  DENTISTRY. 


109 


Fig.  ^^. 

Incisor  and  Canine  Dentures  at  13  and  15  Years  (Table  View). 


no 


AMMAL   DENTISTRY. 


Fig.  78. 
Incisor  and  CaniPi  Dentures  nt  t6  to  20  Years  (Table  View). 


ANIMAl^   DENTISTRY. 


ill 


F;;;,  78a. 
incisor  I^entnre  of  a  Mare  from  IG  to  20  Yearii  (Table  View). 


112 


ANIMAL   DENTISTRY. 


Fig.  79. 
Incisor  Denture   at   t6  to   20  Years,   with    Dark   Line   Showing  Average   In- 
clination. 


ANIMAL  DENTISTRY.  113 

incisors,  with  the  possible  exception  of  the  corners,  are  long 
and  completely  conceal  the  inferior  incisors  from  an  an- 
terior view  when  the  mouth  is  closed,  the  contact  edge  of 
the  superior  incisor  arcade  overlaps  that  of  the  inferior,  and 
finally  the  tables  of  the  central  inferior  incisors  are  becoming 
circular  and  even  flattened  from  side  to  side.     (Figs.  78,  79.) 

Twenty  to  twenty-five  years — The  mouth  presents  all 
the  features  of  the  foregoing  paragraph  with  the  exception 
that  the  enamel  island,  representing  the  last  vestige  of  the 
infundibulum,  has  entirely  disappeared  and  is  replaced  by 
either  a  light  or  dark  spot — the  dental  star — which  repre- 
sents the  obliterated  pulp  cavity.  The  tables  are  round  and 
the  external  enamel  around  them  projects  beyond  the  sur- 
face of  the  dentine  within,  and  the  crowns  of  the  superior 
incisors  are  widely  separated  with  gums  and  are  very  nar- 
row at  the  gingival  end.     (Fig.  79.) 

Old  age — The  mouth  of  an  old  horse  may  present  either 
very  long  or  very  short  (worn  out)  incisor  teeth.  If  long, 
the  implantation  can  be  disturbed  on  manipulation  and  can 
almost  be  extracted  with  the  fingers.  If  short,  the  crowns 
at  the  tables  are  separated  one  from  another  by  the  gums, 
the  crowns  are  round  and  the  tables  of  the  inferior  centrals 
are  flattened  from  side  to  side.  The  canines  are  round  and 
the  molars  are  uneven,  easily  extracted,  and  their  roots  can 
be  felt  along  the  gingival  margin.  Often  a  number  of  molars 
are  absent   from   self-extraction. 

ROUTINE  OF  THE  EXAMINATION  OF  A  HORSE'S 
MOUTH  TO  DETERMINE  THE  AGE. 

I.  The  horse  is  approached  on  the  left  side  and  the  lips 
are  opened  laterally,  the  left  hand  elevating  the  upper  lip  as 
the  right  depresses  the  under  one,  thus  exposing  the  lateral 
aspect  of  the  incisor  arcades.     A  glance  at  the  inclination 


il4 


ANIMAL  DENTISTRY. 


Fig.  79A. 
Incisor  and  Canine  Dentures  at  20  to  25  Years  (Table  View). 


AMIMAJ^  DENTISTRY, 


115 


I'lf;.  So. 
Incisor  Denture  of  an  Old  Ilorsc,  with  Dark  Lines  Showing  the  InclinatioQ 


116 


ANIMAL  DENTISTRY 


will  determine  whctlRT  the  horse  is  old  <•,■  young.  If  young 
a  second  glance  is  taken  to  determine  whether  the  exposed 
teeth  are  permanent  or  temporary. 


Fig.  8i. 
Anterior  View  of  the  Incisor  Denture  of  an  Extremely  Old  Horse. 

2.  Without  releasing  the  hold  the  inspector  steps  to 
the  front  of  the  horse,  elevates  the  upper  lip  with  the  left 
hand  and  slips  the  second  and  third  finger  of  the  right  into 


ANIMAL  DENTISTRY.  II7 

the  interdental  space,  the  first  to  expose  the  superior  ar- 
cade and  the  latter  to  cause  the  horse  to  open  the  mouth 
shghtly.  From  this  position  the  length,  color,  crusta  pe- 
trosa  grooves,  contiguity  of  the  crowns,  and  the  gingival 
margin  of  the  superior  arcade   are    inspected. 

3.  Without  changing  positions  the  left  hand  is  now 
placed  gently  into  the  interdental  space  as  the  right  one 
depresses  the  lower  lip  to  expose  the  tables  of  the  incisor 
teeth  to  determine  the  shape  of  the  tables,  the  absence,  ex- 
istence or  size  of  the  cups,  and  the  shape  of  the  internal 
enamel  surrounding  the  infundibula. 

4.  If  deemed  necessary,  without  changing  the  position 
the  left  hand  is  slipped  upward  along  the  left  molar  arcades, 
to  determine  the  number  and  condition  of  the  molar  teeth. 

ANOMALIES  OF  THE  TEETH,  NATURAL  AND 
ARTIFICIAL. 

Nature's  anomalies  in  dental  evolution  and  retrogression 
are  of  such  common  occurrence  that  any  set  rules  for  the 
determination  of  age  will  frequently  mislead  the  diagnos- 
tician. This  is  especially  the  case  when  one  or  two  features 
of  dental  growth  and  wear  are  depended  upon.  The  com- 
mon anomalies  of  the  teeth  are: 

(i)     Anomalies  of  eruption. 

(2)  Anomalies  of  the  texture  of  the  dental  tissues. 

(3)  Anomalies  of  the  infundibula. 

(4)  Anomalies  of  the  cups  of  the  infundibula. 

(5)  Anomalies  due  to  the  character  of  the  food. 

(i)  Eruption  of  the  teeth  will  vary  sHghtly  in  dif- 
ferent breeds  and  from  climate  and  artificial  influences.  In 
the  well-bred  horse,  the  thoroughbred,  hackneys  and  Ameri- 
can trotters,  in  which  the  development  is  forced  from  colt- 
hood,  the  temporary  teeth  erupt  several  months  earlier  than 
in  the  horse  reared  under  more  natural  conditions,  and  the 


118  ANIMAL   DE.XTIS'I'RV. 

same  precocity  will  be  observed  in  the  shecUbni,^  of  the  tem- 
porary teeth,  from  tlie  increased  amount  (jf  hard  food  in- 
gested at  an  age  when  the  teeth  are  still  defective  in  tex- 
ture. In  the  one-year-old  race  horse  that  is  trained  and 
fed  to  force  the  development  of  the  muscular  system  the 
teeth  will  share  in  the  development  providing  the  imnatura'. 
requirement   docs  not   impair  the   general   health. 

(2)  The  texture  of  the  teeth  varies  in  different  animals 
of  the  same  class  reared  under  the  same  conditions,  from 
causes  too  obscure  to  recognize.  Deficiency  in  the  inorganic 
proximate  principles  of  food  in  certain  districts  has  been 
observed  to  yield  horses  with  soft  teeth.  The  variation  in 
the  texture  of  the  teeth  will  either  hasten  or  retard  the 
retrogression  of  the  teeth.  When  the  teetli  are  hard  the 
events  by  wdiich  age  is  determined  will  be  retarded,  and  as 
a  consequence  the  animal  will  a])pear  young.  AMien  the 
teeth  are  soft  the  reverse  occurs  and  the  animal  appears 
older.  The  anomalies  caused  by  the  varied  density  of  the 
tooth  sul)stance  are  precocious  or  retarded  changes  in  the 
cups,  infundibula.  shape  of  the  taldcs  and  length  of  the 
crowns.  One  of  the  most  pronounced  resu'ts  of  soft  teeth 
is  the  shortening  instead  of  elongation  of  the  incisor  crowns 
as  the  animal  becomes  old. 

(3)  The  infundibula  of  the  incisor  teeth  may  vary 
greatly  as  to  their  depth.  They  may  be  very  shallow  in 
some  animals  and  very  deep  in  others,  and  thus  prove  mis- 
leading when  depended  upon  a'one  in  the  determination  of 
age. 

(4)  The  cups  of  the  infundibula  are  equally  sul)ject  to 
variations,  due  to  the  amount  of  crusta  petrosa  in  the  bot- 
tom of  the  infundibula.  In  some  teeth  the  infundibula  are 
almost  full  of  crusta  petrosa,  while  others  contain  but  a 
small  amount.  AMien  full  the  cup  disappears  early,  and 
when  empty  it  persists  longer.     This  anomaly  is  not  con- 


ANIMAL  DENTISTRY. 


119 


fusing  if  the  shape  of  the  infundibula  is  taken  into  account. 
(5)     Character  of  the  food  will  hasten  or  retard  the  wear 
of  the  teeth   to  a   remarkable   degree.      Grazing,  which   re- 
quires the  use  of  the  incisor  teeth  to  detach  the  food,  has  a 


Fig.  8 1  a. 
Gouge. 


Fig.  81B. 
Bishoping  Drills. 


precocious  influence,  while  stable  feeding,  which  exacts  but 
little  work   from   the   incisors,   retards  the  wear. 

Artificial  anomalies  refer  to  alterations  in  the  appearance 
of  the  incisor  teeth  by  the  use  of  instruments.  Deviation 
from   the  normal   may  result:   from  : 

(i)     Shortening  of  the  crowns  of  the  incisors,  espe- 


120  ANIMAL   DENTISTRY. 

cially  tlic  superior,  with  the  incisor  nipper  and  file. 

(2)  Polishing  the  anterior  surface  of  the   superior 
incisors. 

(3)  Renewal  of  the  cups  by  drillini;-  and  staining. 

1.  Shortening  of  the  crowns  of  the  superior  incisors  will 
deceive  only  the  novice  or  the  careless  expert.  The  ar- 
tificially shortened  crown  is  promptly  recognized  by  the  in- 
terrupted contact  of  the  anterior  margin  of  the  arcades,  if 
not  by  the  other  retrogressive  changes  which  cannot  be  ef- 
faced. The  operation  is  performed  with  an  ordinary  incisor 
nipper  and  file.  The  first  step  is  to  cut  off  the  anterior  end 
of  the  superior  corners  where  they  contact  the  laterals,  and 
then  file  them  to  the  length  decided  upon.  Then  using  this 
length  as  a  guide,  a  groove  is  filed  across  the  entire  arcade, 
over  the  laterals  and  centrals.  The  teeth  are  then  cut  oflf 
along  the  groove  and  filed  to  a  regular,  smooth  edge,  and 
beveled  backwards  to  give  the  appearance  of  a  normal  su- 
perior table.  If  the  nipper  alone  is  used  without  first  groov- 
ing the  arcade,  the  enamel  may  chip  upward  and  ruin  the 
appearance  of  the  whole  arcade. 

2.  Polishing  the  crowns — After  shortening  the  arcade 
the  anterior  face  is  scraped  of  all  its  tartar  and  crusta  pe- 
trosa  with  a  curette,  and  then  wdiitened  with  emery  paper 
to  give  the  appearance  of  young  teeth.  This  operation  is 
also  performed  with  a  small  revolving  emery  wdieel  applied 
to  the  flexible  shaft  of  a  dental  engine.  By  this  means  the 
grooves,  as  well  as  the  incrustations,  can  be  removed.  The 
typical  bluish-white  color  of  young  enamel  can,  however, 
not  be  imitated,  and  besides,  the  yellow  color  will  soon  re- 
turn. 

3.  Renewal  of  the  cups  (Bishoping)  is  the  most  impor- 
tant of  the  artificial  attempts  to  make  horses  appear  younger, 
and  if  performed  intelligently  upon  horses  that  are  not  too 
old,  together  with  the  above  operations,  even  the  vaunted 


ANIMAL  DENTISTRY. 


121 


expert  may  blunder.  The  operation  consists  of  cutting 
large  cups  in  the  inferior  corners,  smaller  ones  in  the  laterals 
and  mere  dots  in  the  centrals  and  then  staining  them  with 


l-'id.    H2.\. 

Wheel  Drill. 


Fig.  82. 
Dental    Engine. 


Fig.  82B. 
The  Polishing  Wheel. 


silver  nitrate.  The  cupping  process  is  performed  with  an 
engraver's  gouge,  revolving  hand  drill,  or  by  the  modern 
ingenious  implement  in  vogue  in  the  Chicago  horse  market, 


122 


ANLMAL   J>1:NTISTRY. 


consisting  of  the  foot  engine  used  by  human  dentists, 
equipped  with  a  circular  cutting  wheel,  by  which  cups  of  per- 
fectly normal  shape  and  size  can  be  made. 

Modus  operandi:     llic  horse  is  backed  into  a  single  stall 


Fig.  83. 
An   8-Year-Olcl    Mouth    Made    "6"   by   "Bishoping." 

and  secured  in  the  dental  halter.  An  assistant  works  the 
dental  engine  with  the  foot.  The  operator  holding  the  hand- 
piece of  the  flexible  shaft  in  the  right  hand  and  the  jaw  in 


Fic.  84. 
A  9  or  lo-Year-Old  Moutli  Made  "7"  bj'  '"Bishoping." 

the  Other,  cuts  first  a  large  elliptical  cup  with  sharp  commis 
sures  in  the  table  of  the  corner  incisors,  then  smaller  ones 
in  the  laterals  and  small  dots  in  the  centrals.    As  the  wheel 
revolves  with  great  velocity,  the  cupping  is  the  work  of  but 


ANIMAL  DENTISTRY.  i23 

a  moment,  if  the  horse  stands  complacently.  When  the  cor- 
ner tooth  has  but  a  small  table  it  is  enlarged  by  filing  and 
the  cup  is  cut  across  its  entire  length.  The  cup  in  the  cor- 
ners is  frequently  made  with  a  rounded  belly  internally  and 
a  sharp  commissure  externa'iy  to  give  a  more  confusing  if 


Fig.  85. 

not  more  natural  appearance.  When  the  cupping  process 
is  complete  the  arcade  is  dried  and  kept  free  from  saliva  by 
wrapping  the  jaw  behind  the  teeth  with  a  cloth  or  towel. 
The  cups  are  then  stained  by  applying  a  saturated  solution 
of  silver  nitrate  with  a  stick  and  then  drying  it  immediately 


Fig.  86. 
Effect  of  "Rishoping"   Teeth   of  9  to   12- Year-Old  Horses. 

by  plunging  the  head  of  a  burning  match  into  it.  The  drying 
process  immediately  blackens  the  cavity.  If  the  stain  flows 
over  the  table  of  the  tooth  it  is  filed  ofT. 

Shortening,  polishing,  cupping  and  staining  tiie  incisor 
teeth  of  a  nine  or  ten-year-old  horse  may  be  so  cleverly  per- 


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126 


ANIMAL  DENTISTRY. 


formed  that  the  most  circumspect  study  of  the  mouth  may- 
fail  to  detect  the  alteration.  In  these  cases  the  cupping  is 
limited  to  the  removal  of  the  crusta  petrosa  within  the  in- 
fundibula,  thus  leaving  the  cup  with  a  perfect  enamel  bound- 
ary. At  that  age  the  other  retrogressive  changes  are  not 
pronounced  and  afford  but  litt'e  evidence  to  guide  the  diag- 
nostician.    (See  Figs.  83,  84,  85,  86.) 


Fig.  87. 
The    Ridiculous    Effect    of    "Bishoping"    Aged    Horses. 

When  horses  are  past  the  age  of  twelve  years  the  results 
of  these  operations  are  readily  detected  by  the  interrupted 
contact  of  the  incisor  arcades  and  especially  by  the  angle  of 
inclination,  which  is  never  altered  by  any  natural  anomaly 
and  which  cannot  be  artificially  changed.  The  shape  of  the 
tables  and  the  absence  of  enamel  around  the  cup  will  also 
lead  readily  to  detection  of  the  fraudulent  attempts  to  make 
very  old  horses  appear  younger.      (See  Fig.  87.) 


CHAPTER  IV. 

FUNCTION  OF  THE  TEETH. 

The  teeth  have  but  a  passive  function  to  perform  as  ac- 
cessory organs  of  prehension,  mastication  and  insaliva- 
tion,  and  as  organs  of  defense.  Their  uses  are  similar  in  all 
species,  varying  but  slightly  in  detail. 

The  incisors  serve  the  general  purpose  of  holding  food, 
after  the  lips  or  tongue  have  gathered  it  between  them,  and 
as  a  jerk  of  the  head  detaches  it.  In  the  ingestion  of  de- 
tached food  they  serve  no  useful  purpose  in  any  of  the  do- 
mestic animals.  In  all  the  domestic  mammals  except  rumi- 
nants they  are  important  organs  of  defense,  and  as  such  they 
are  most  useful  in  the  soliped.  The  incisors  of  carnivora  are 
so  much  shorter  than  the  canines  that  the  latter  inflict  the 
greatest  harm  to  an  enemy. 

The  canines  of  solipeds  are  common  only  to  males,  in 
v.diich  animals  they  have  no  special  function  to  perform.  In 
the  carnivora  and  omnivora  they  serve  the  useful  purpose 
of  tearing  attached  food  preparatory  to  mastication,  besides 
constituting  the  principal  organs  of  defense.  In  these  ani- 
mals they  are  common  to  both  sexes  and  they  lock  over  each 
other  in  a  manner  to  hold  fast  to  any  object  into  which  they 
are  imbedded. 

The  molars  of  herbivora  are  the  mill-stones  of  the 
mechanism  of  mastication.  The  wide,  roughened  tables  of 
the  superior  molars,  and  the  series  of  strong  muscles  which 
move  the  inferior  ones  upon  them,  constitutes  the  principal 
features  of  a  perfect  grinding  apparatus  necessary  to  the 
welfare  of  animals  ingesting  coarse,  fibrous  food.  In  these 
animals  the  molars  grind  the  food  perfectly,  carefully  and 

127 


128  ANIMAL   DENTISTRY. 

persistently,  and  at  the  same  time  incorporate  it  with  the 
abundant  saliva  essential  to  the  proper  digestion  of  amyla- 
ceous food.  In  ruminants  the  food  is  first  passed  by  the 
molars  with  only  nominal  comminution,  but  when  it  is  re- 
gurgitated during  rumination  it  is  as  carefully  masticated  as 
in  the  non-ruminating  animal.  Besides  the  function  of  mas- 
tication and  insalivation,  the  molars  might  correctly  be  class- 
ified as  tactile  organs,  as  they  readily  detect  the  presence  of 
undesirable  particles  of  food. 

In  the  carnivora  the  molars  serve  to  crack  hard  objects, 
as  bones,  into  smaller  particles  and  to  divide  large  pieces  of 
flesh  into  smaller  ones  simultaneously  with  surrounding  the 
particles  with  a  slimy  coat  of  saliva  to  facilitate  deglutition. 
In  these  animals  they  are  not  essential  organs,  as  the  food 
may  be  bolted  without  material  impairment  of  the  general 
health,  while  in  the  herbivora  the  molars  are  as  essential  to 
the  life  of  the  animal  as  any  of  the  internal  digestive  organs. 

PREHENSION. 

The  function  of  prehension  is  performed  by  the  lips,  in- 
cisor teeth,  canine  teeth  and  tongue.  When  the  food  has 
passed  the  incisors  and  canines,  and  the  mouth  is  closed,  it  is 
drawn  backward  to  the  molars  by  suction.  The  organs  of 
prehension  named  in  the  order  of  their  importance  in  the  dif- 
ferent animals  are  as  follows: 

Horse:  (i),  the  lips;  (2),  the  incisor  teeth;  (3),  the 
tongue. 

Ruminants:  (i),  the  tongue;  (2),  the  incisor  teeth  and 
dental  pad;  (3),  the  lips. 

Carnivora:  (i),  the  canine  teeth;  (2),  the  tongue;  (3), 
the  incisor  teeth;  (4),  the  lips.  In  the  ingestion  of  liquids 
the  tongue  alone  performs  the  function  by  dashing  the  liquid 
well  backward  into  the  mouth. 


ANIMAL   DENTISTRY.  129 

Omnivora:  (i),  the  incisor  teeth;  (2),  the  canine 
teeth;  (3),  the  Hps;  (4),  the  tongue. 

(In  sheep  and  goats  the  lips  are  very  motile  and  serve  to 
gather  attached  food  as  in  the  horse.) 

MECHANISM  OF  MASTICATION. 

The  organs  of  mastication  comprise:  The  superior  max- 
illary, the  inferior  maxillary,  the  premaxilla,  the  molar  teeth, 
the  tongue,  the  hard  palate,  the  cheeks,  and  the  masseter, 
the  internal  pterygoid,  the  temporalis,  the  digastricus,  the 
external  pterygoid,  the  stylo-maxillaris  and  the  sterno- 
maxillaris  muscles. 

The  superior  maxillary  is  an  immovable  bone,  closely 
united  by  sutures  to  its  contiguous  facial  and  cranial  bones, 
and  to  its  fellow  by  a  wide,  flat  process  extending  across  the 
mouth  to  form  its  bony  roof.  It  receives  into  six  deep  cavi- 
ties the  imbedded  portions  of  the  superior  molar  arcade,  and 
with  its  fellow  and  premaxilla  constitutes  the  upper  jaw. 
Its  function  is  to  hold  taut  the  superior  molars  and  to  form 
the  roof  of  the  mouth. 

The  inferior  maxillary  is  a  movable  bone  articulating 
with  the  squamous  temporal  by  a  diarthrosis  having  imper- 
fect rotatory  and  perfect  ginglymoid  motion.  It  is  a  single 
bone  consisting  of  a  small  body  anteriorly  with  two  large 
branches  extending  pwDsteriorly  to  the  temporo-maxillary 
articulation.  At  the  anterior  extremity  of  the  body  it  re- 
ceives the  six  incisor  teeth  and  along  the  superior  margin  of 
each  branch  the  six  inferior  molars.  Its  function  in  masti- 
cation is  to  serve  as  a  carriage  for  the  inferior  molars,  a 
medium  for  the  attachment  of  the  muscles  which  move  it  and 
to  assist  in  forming  the  bony  boundary  of  the  mouth. 

The  premaxilla  is  an  irregular  bone,  which,  with  its  fel- 
low completes  the  upper  jaw  anteriorly  and  contains  the 


130  ANIMAL    DENTISTRY. 

alveolar  cavities  for  superior  incisor  tcctli.  It  consists  of  a 
body  and  two  branches  extending  backward.  The  upper 
branch  passes  upward  and  backward  along  the  superior 
maxilla  to  the  base  of  the  nasal  peak,  where  it  enters  into  the 
formation  of  the  maxillo-nasal  notch.  The  lower  branch  is 
a  thin  plate  loosely  attached  to  its  fellow  and  the  superior 
maxilla  to  complete  the  roof  of  the  mouth  anteriorly. 

The  tongue  of  animals  is  a  very  strong,  motile,  musculo- 
membranous  organ,  having  a  fixed  attachment  to  the  spur 
process  of  the  hyoid  bone  posteriorly,  and  a  free  extremity 
anteriorly.  It  is  held  to  the  floor  of  the  mouth  by  its  mucous 
membrane.  Its  upper  surface  is  thickly  paved  with  epi- 
thelium. It  is  a  tactile,  gustatory,  prehensile  and  masticating 
organ.  In  m.astication  it  serves  the  useful  purpose  of  keep- 
ing the  food  between  the  molars  while  grinding,  and  to  assist 
in  its  backward  passage  when  mastication  is  complete. 

The  hard  palate  is  a  dense  fibrous  cushion  covering  the 
entire  roof  of  the  mouth  from  the  incisor  teeth  to  the  soft 
palate.  It  presents  a  number  of  transverse  bars  which  meet 
in  a  longitudinal  raphe.  It  serves  the  purpose  of  preventing 
food  from  slipping  freely  outward,  and  to  assist  the  tongue  in 
passing  food  backward. 

The  cheeks  are  composed  of  the  buccinator  muscle  cov- 
ered externally  with  the  skin  and  internally  with  the  buccal 
mucous  membrane.  It  is  a  loose  curtain  attached  just  be- 
yond the  alveolar  border  of  each  molar  arcade.  In  masti- 
cation it  serves  to  keep  the  food  between  the  teeth  and  to 
complete  the  lateral  boundaries  of  the  mouth. 

The  masseter  muscle  is  a  thick,  wide  and  short  muscle 
located  on  the  lateral  aspect  of  the  lower  jaw.  Its  fixed  at- 
tachment is  the  maxillary  spine  and  zygoma  and  its  movable 
insertion  the  external  face  of  the  lower  jaw.  Its  function  is 
that  of  closing  the  jaws  and  drawing  the  inferior  maxillary 
slightly  forward. 


ANIMAL   DENTISTRY.  131 

The  pterygoid  internus  muscle  occupies  the  same  relative 
position  on  the  internal  aspect  of  the  ramus  as  the  masseter 
does  externally.  Its  fixed  attachment  is  the  palatine  crest 
and  the  movable  insertion  the  internal  face  of  the  lower 
jaw.  Its  function  is  that  of  producing  lateral  motion  and  as- 
sisting the  masseter  to  close  the  jaws,  as  follows:  The  left 
muscle  acting  alone  draws  the  jaw  to  the  right  and  the  right 
one  to  the  left,  and  when  acting  together  they  assist  the 
masseter  in  closing  the  mouth. 

The  temporalis  muscle  occupies  the  space  over  the  parie- 
tal bones,  and  is  inserted  to  the  coronoid  process  and  anterior 
border  of  the  ramus  of  the  jaw.  Its  function  is  that  of  clos- 
ing the  jaw,  and  when  acting  singly  it  produces  lateral  mo- 
tion. 

The  pterygoid  extemus  is  a  short,  thick  muscle  situated 
internally  and  in  front  of  the  temporo-maxillary  articulation. 
It  originates  on  the  sphenoid  bone  and  is  inserted  at  the  neck 
of  the  jaw  just  below  the  condyle.  Acting  together  they 
pull  the  jaw  forward  and  singly  they  produce  a  lateral  mo- 
tion. 

The  stylo-maxillaris  originates  at  the  styloid  process  of 
the  occipital  and  is  inserted  to  the  posterior  border  of  the 
ramus  of  the  jaw.  Its  function  is  that  of  drawing  the  jaw 
backward  and  depressing  it. 

The  digastricus  muscle  is  located  in  the  maxillary  space, 
originating  on  the  styloid  process  with  the  stylo-maxillaris 
and  is  inserted  along  the  inner  border  of  the  ramus  toward 
the  symphysis.  Its  function  is  that  of  retracting  and  de- 
pressing the  jaw. 

The  sterno-maxillaris  muscle  originates  on  the  cariniform 
cartilage  of  the  sternum  and  is  inserted  at  the  angle  of  the 
jaw.    Its  function  is  that  of  depressing  the  jaw. 

The  lower  jaw  is  moved  in  every  direction  by  the  muscles 
of  mastication;  it  is  advanced,  retracted,  elevated,  depressed 


132  ANIMAL   DENTISTRY. 

and  drawn  to  either  side  at  will.  In  ruminants  the  lateral 
motion  is  pronounced  while  in  the  carnivora  it  is  prevented 
by  the  interlocking^  of  the  canine  teeth,  the  beveled  molars 
and  the  ginglymoid  character  of  the  articulation.  In  soli- 
peds  the  lateral  motion  is  nominal.  The  antero-posterior 
motion  is  prominent  in  rodents  and  is  possible  to  a  normal 
degree  in  herbivora.  The  upward  movement,  which  is  the 
most  forcible,  is  of  course  a  prominent  movement  in  all 
animals,  but  is  an  exceptionally  powerful  one  in  the  solipeds 
and  ruminants. 

Mastication  is  effected  in  about  the  following  manner. 
The  mouth  is  opened  by  gravity,  aided  by  the  stylo-maxil- 
laris  and  digastricus  muscles;  it  is  then  swamg  to  the  side 
and  slightly  forward  l)y  the  pterygoids,  temporalis  and  mas- 
seter,  and  then  diagonally  upward  !)y  the  combined  effort  of 
the  masseter,  internal  pterygoid  and  temporalis.  During 
these  movements  the  tongue  and  buccinator  are  engaged  in 
keeping  the  bolus  in  position  to  be  caught  between  the  teeth 
as  they  come  together. 

Mastication  is  unilateral,  only  one  side  of  the  mouth  is 
used  at  a  time.  Herbivora  will  chew^  on  one  side  for  a  few 
minutes  and  then  shift  the  next  bolus  to  the  other,  at  their 
will. 


CHAPTER  V. 

DENTAL  DIAGNOSIS. 

Examination  of  the  incisors  (see  page  113). 

Examination  of  the  horse's  mouth  preceding  the  usual 
dental  operations  is  done  in  the  standing  position,  by  palpa- 
tion and  inspection. 

Palpation  of  the  mouth. — As  the  horse's  mouth  is  a 
dark,  deep  cavern  its  examination  for  the  detection  of  the 
common  irregularities  must  depend  chiefly  upon  manual  ex- 
ploration. For  this  purpose  the  mouth  speculum  or  a  gag 
may  be  used.  The  expert,  however,  requires  neither,  but 
passes  the  hand  with  the  greatest  freedom,  ease  and  leisure 
to  any  and  all  parts  of  the  mouth,  without  inconvenience  to 
the  horse  or  injury  or  danger  to  himself.  To  accomplish 
that  valuable  attainment  the  halter  is  removed  and  the  head 
is  held  from  being  thrown  upward  by  an  assistant  holding 
one  hand  on  the  nose  and  the  other  on  the  poll.  The  diag- 
nostician stands  directly  facing  the  horse,  and  passes  the 
right  hand  into  the  left  commissure  of  the  mouth,  across  the 
interdental  space  into  the  space  between  the  tongue  and 
molar  teeth  on  the  opposite  (left)  side.  The  palm  of  the 
hand  faces  the  teeth  and  the  dorsum  the  tongue.  In  this 
position  the  tongue  of  the  horse  is  not  forced  into  any  un- 
comfortable attitude  and  the  mouth  is  not  forcibly  opened. 
The  hand  may  then  be  passed  gently  backward  to  the  fauces 
and  the  fingers  may  be  extended  over  the  tables  of  the  teeth 
without  danger  or  injury.  The  secret  of  success  is  in  not 
opening  the  mouth  too  wide  and  in  engaging  the  horse  bv 
keeping  the  hand  constantly  moving.     When   the   hand  is 

ass 


134 


ANIMAL  DENTISTRY. 


kept  stationary  in  the  mouth  resistance  is  immediately  of- 
^ei'ed. 

The   right  side  is  palpated  with  the  left  hand  and  vice 
versa.     Prior  to  the  molar  examination  or  immediately  after, 


^yi^ 


Fig. 
"  Search  Lights." 

tne  interdental  space,  first  below  and  then  above,  is  palpated 
with  the  palmar  surface  of  the  thumbs  to  locate  possible  bit 
lesions  or  wolf  teeth. 

The  novice  may  use  the  mouth  speculum,  which  will  ad- 
mit of  free  palpation  of  the  teeth  with  the  exception  of  the 


ANIMAL   DENTISTRY.  I35 

external  borders  of  the  molar  arcades.  The  hand  cannot  be 
admitted  freely  into  the  mouth  unless  the  speculum  is  opened 
wide  enough  to  provoke  resistance,  and  besides  the  cheek  is 
drawn  taut  against  the  teeth  and  prevents  palpation  of 
the  borders  of  the  molars. 

Inspection  of  the  mouth. — Beyond  the  first  two  molars 
the  mouth  cannot  be  satisfactorily  inspected  in  the  standing 
position.  Only  gross  abnormalities  can  be  seen,  and  these 
only  to  an  unsatisfactory  degree.  With  the  aid  of  a  mouth 
speculum  and  artificial  light, — a  reflector  or  incandescent 
light, — with  the  head  raised  and  the  operator  standing  on  an 
elevation  it  is  possible  to  inspect  the  teeth,  but  in  this  pro- 
cedure the  tongue  and  the  resistance  to  such  forcible  manip- 
ulations offered  by  the  horse,  materially  interfere.  A  perfect 
inspection  of  the  mouth  can  only  be  made  in  the  recumbent 
posture  with  the  head  turned  upward  and  the  speculum  ad- 
justed, and  then  only  by  the  aid  of  good  light, — a  reflector  if 
necessary.  By  pulling  the  tongue  to  first  one  side  and  then 
the  other,  every  part  of  the  mouth  can  be  seen  and  felt,  and 
in  addition  abnormalities  can  be  searched  for  with  steel  picks. 

DENTAL  INSTRUMENTS— THEIR  USES. 

FLOATS  AND  FLOAT  BLADES. 

Floats  are  the  principal  instruments  of  the  animal  dentist. 
They  are  to  the  animal  dentist  what  the  drill  and  dental 
engine  are  to  the  human  dentist.  The  float  is  a  simple  con- 
trivance consisting  of  a  handle,  shaft  and  head  to  receive 
the  blade  which  may  be  either  a  rasp  or  file.  The  entire 
length  should  not  exceed  nineteen  inches,  divided  as  follows: 
Handle,  sMi  inches;  shaft,  10%  inches,  and  head,  3  inches. 
The  head  is  open  to  receive  the  blade  at  either  end  and  is 
perforated  with  two  openings  to  receive  the  screws  with 
which  the  blade  is  kept  taut.    There  are  many  patent  affairs 


136 


ANIMAL    DENTISTRY. 


on  the  market,  some  simple  and  others  complex,  which  hold 
the  blade  solid  by  various  means.  Some  are  equipped  with  a 
mechanism  by  which  the  head  can  be  placed  at  different 
angles  with  the  aim  of  combining  two  instruments  in  one,  i, 
e.,  the  straight  and  the  angular  float.  All  these  inventions 
to  date  are  but  poor  imitations  of  the  old  reliable  simple 
screw-head  float,  and  are  neither  durable  nor  practical,  and 
few  will  hold  the  blade  as  solid  as  the  old  pattern. 

These  instruments  are  generally  designated  as  the  House 
floats;  they  have  been  in  use  for  more  than  thirty  years,  and 
as  they  offer  but  little  chance  for  improvement  they  will 
probably  always  retain  the  prestige  of  being  the  most  satis- 


FiG.  89. 


Fig.  89a. 
Straight  and  Angular  Floats,  with  Lines  showing  the  Proper  Angle  of 

Each. 

factory  instrument  of  their  kind.  Two  styles  are  recom- 
mended—the straight  float  and  the  angular  float. 

The  Straight  Float  is  used  to  file  the  lower  arcades 
and  the  posterior  two-thirds  of  the  superior  arcades,  and  to 
facilitate  its  passage  to  the  remotest  teeth  its  head  must  be 
on  a  straight  line  with  the  handle,  i.  e.,  when  the  handle  lies 
flat  upon  a  plane  the  head, — face  downward, — must  do  like- 
wise throughout  its  entire  length.  The  posterior  end  of  the 
arcades,  especially  the  inferior,  cannot  be  reached  with  a 
float  of  any  other  shape  without  opening  the  horses's  moutJi 
wide  enough  to  provoke  resistance. 

The  Angular  Float  is  used  to  file  the  anterior  third  or 
half  of  the  superior  arcades,  which,  owing  to  the  inward  cur- 


ANIMAL   DENTISTRY. 


137 


vature  of  their  external  borders,  cannot  be  conveniently 
reached  with  an  instrument  of  any  other  shape.  The  angular 
float  should  be  of  the  same  size  and  length  as  the  straight 
one.  When  its  head  lies,  face  downward,  upon  a  plane,  the 
center  of  the  handle  should  be  elevated  two  and  one-half 
inches  above  the  plane.  The  short-handled  floats  of  greater 
angles  are  much  less  convenient. 

The  Float  Blades  should  be  of  the  rasp  variety,  tempered 
hard  enough  to  wear  well  and  yet  not  so  hard  as  to  chip 
from  filing  the  hard  enamel  points  of  the  molars.  In  the 
straight  float  the  cutting  edges  of  the  rasp  must  point  back- 
ward,— toward  the  handle, — and  in  the  angular  they  must 
point  forward.  This  arrangement  is  intended  to  train  the 
hands  to  make  the  float  cut  on  its  outward  course  instead  of 
its  inward  course,  and  thereby  prevent  prodding  the  back  of 
the  mouth. 


Fig.  90. 

THE  FLAT  FILE  AND  RASP. 

The  flat  file  and  rasp  should  be  twelve  inches  long, 
rounded  at  the  extremities  and  have  a  file  on  one  side  and 
a  rasp  on  the  other.  It  is  used  to  round  the  first  superior 
and  first  inferior  molars,  and  to  shorten  the  canines  and  in- 
cisors. 

THE  CLOSED  MOLAR-TRIMMER  OR  CUTTER. 

The  closed  trimmers  are  nineteen  to  twenty  inches  long, 
including  the  handles,  and  have  a  head  consisting  of  a  box 


138  ANIMAL    DENTISTRY. 

joint  and  two  cutting  jaws,  one  to  one  and  a  quarter  inches 
long,  which  come  together  in  perfect  apposition.  The  cut- 
ting surface  is  dropped  three-eighths  of  an  inch  below  the 
level  of  the  instrument  better  to  enable  the  grasping  of  small 
points.  It  should  be  made  with  a  box  joint,  the  center  of 
which  is  no  more  than  two  and  a  quarter  inches  from  the  end 
of  the  cutting  jaws.  The  forks  and  handles  should  be  of  no 
less   than  five-sixteenths  inch   steel. 

This  instrument  was  primarily  intended  to  trim  the 
enamel  points  along  the  arcades,  both  superior  and  inferior, 
and  it  is  still  being  used  for  this  purpose  by  some  veterinary 
practitioners.  Its  use  for  this  purpose  cannot,  however,  be 
sanctioned,  owing  to  the  difficulty  of  placing  them  accurately 
upon  the  small  enamel  points  located  posteriorly  on  the  ar- 


FiG.  91. 

Closed  Molar  Trimmer. 

cades.  The  smallness  of  the  points,  the  motility  of  the  head 
and  the  great  distance  between  the  hands  and  the  cutting  end 
of  the  instrument,  makes  their  applicability  difficult  in  the 
hands  of  the  unskilled.  Even  in  the  hands  of  the  skilled  den- 
tist their  use  amounts  to  the  cutting  of  whatever  happens  to 
be  caught  between  the  jaws. 

The  closed  trimmer  should  be  used  only  in  cutting  the 
projections  at  the  extremities  of  the  arcades — the  first  su- 
perior and  sixth  inferior  molars — for  which  purpose  they  are 

indispensable. 

THE   OPEN   MOLAR-CUTTER. 

The  open  molar-cutter  of  the  double-lever  variety  is  also 
an  indispensable  part  of  the  dental  outfit,  and  owing  to  the 
laborious  work  it  must  perform  it  should  be  powerful  enough 
to  cut  any  projecting  tooth   promptly.     The   style   recom- 


ANIMAL   DENTISTRY. 


139 


mended  is  twenty-four  to  twenty-five  inches  long  and  has  a 
head  consisting  of  a  box  joint  and  two  cutting  jaws  no  more 
than  one  inch  long  which  approximate  within  one-quarter  of 
an  inch  when  the  instrument  is  closed.  Six  inches  from  the 
center  of  the  box  joint  is  a  second  one.  to  increase  the  lever- 


FiG.  92. 
The  Open  Molar  Lever  Cutter. 

age.  The  fork  between  the  joints  is  of  three-quarter  inch 
(square)  bar  steel,  while  that  from  the  last  joint  and  handles 
is  of  five-sixteenth  steel. 

This  instrument  must  possess  strength  at  the  expense  of 
its  neatness.     It  can  be  opened  wide  enough  to  receive  any 


SHARP  4  SMITH,  CHICAGO 


Fig.  92A. 

Plain  Open  Molar  Cutter. 

elongation  of  the  horse's  molars  and  will  promptly  cut,  with 
only  nominal  effort,  any  tooth  its  jaws  may  grasp. 

The  single  joint  open  molar-cutters,  unless  made  much 
stronger  and  longer,  will  frequently  disappoint  the  operator 
and  will  always  require  a  number  of  strenuous  efforts  before 
a  large  tooth  will  yield. 


140 


ANIMAL   DENTISTRV. 


THE  WOLF-TOOTH  SEPARATOR   AND  FORCEPS. 

The  wolf-tooth  separator  is  a  nine-inch  instrument  hav- 
ing a  box  joint  and  bayonet-point  head,  which  contains  two 
cutting  or  wedging  jaws  approximating  each  other  closely 
at  tlie  end  but  open  slightly  along  the  cutting  surface.  This 
instrument  is  made  use  of  to  extract  wolf  teeth  hy  wedging 
them  between  the  wolf  tooth  and  molar  to  disturb  the  alveo- 


FiG.  93. 
Wolf-Tooth  Separator. 

lar  implantation  and  then  pry  them  out.  Their  use  to  dis- 
turb the  tooth  may  precede  the  use  of  the  ordinary  wolf 
tooth  extractor  which,  in  view  of  the  utility  of  the  separator, 
may  be  entirely  dispensed  with  in  veterinary  dentistry.  The 
separator  may,  in  addition,  be  used  to  extract  the  shedding 


t'lr,.  93 A. 
Wolf-Tooth   Forceps. 

incisors,  shedding  molar  caps,  incisors  and  canines  of  dogs 
and  fractured  incisors  of  horses. 

THE   MOLAR   SEPARATOR. 

The  molar  separator  is  twenty  inches  long  and  has  a 
head  consisting  of  a  box  joint  and  two  wedge-shaped  jaws, 
projecting  at  a  right  angle,  the  edges  of  which  come  together 
when  the  instrument  is  closed.  It  is  used  for  the  purpose  of 
loosening  the  decayed  molar  prior  to  the  application  of  out- 


ANIMAL   DENTISTRY 


141 


ward  force  with  the  extracting  forceps.  Its  jaws  are  wedged 
alternately,  into  the  interdentia  on  either  side  of  the  de- 
cayed tooth  until  the  implantation  is  disturbed. 


Fig.  94. 
Open   Molar    Separator,  for    Superior    Arcades. 

THE  CLOSED  MOLAR  EXTRACTOR. 

The  closed  molar  extractor  is  twenty  inches  long  and  has 
jaws  no  more  than  one  inch  long  and  five-eighths  of  an  inch 
wide,  projecting  at  a  right  angle  from  the  head.     The  forks 


Fig.  94 a. 
Closed  Molar  Separator,  for  Inferior  Arcades. 

and  handles  are  strong  enough  to  prevent  springing  when 
pressed  forcibly  together.  The  jaws  approximate  within  one- 
eighth  of  an  inch  and  are  furrowed  internally  to  prevent 
slipping  from  the  tooth.     This  instrument  is  indispensable  in 


Fig.  95. 
Closed  Molar  Extractor. 

the  extraction  of  molars,  most  of  which  are  split  into  narrow 
plates  that  cannot  be  held  with  an  open  forceps.  It  is  used 
chiefly  to  extract  split  molars,  but  may  be  utilized  to  ad- 
vantage even  when  the  crown  is  whole.     The  dental  equip- 


142 


ANIMAL   DENTISTRV 


ment  containing  only  one  extractor  should,  therefore,  con- 
lain  the  closed  variety  instead  of  the  open,  which  can  only  be 
applied  in  the  extraction  of  molars  havin^::  full  crowns. 


Fig.  96. 
Closed  Molar  Extractor,  with  Curved  Handles. 

THE  OPEN  MOLAR  EXTRACTOR. 
The  open  molar  extractor  answers  the  same  general  de- 
scription as  the  closed,  with  the  exception  that  the  jaws  are 
five-eighths  of  an  inch  apart  when  the  instrument  is  closed, 
and  that  the  forks  form  an  abrupt  drop  of  one  inch,  five 
inches  from  the  head.  The  object  of  the  curved  or  drop 
forks  is  to  prevent  the  handles  from  striking  the  incisor  teeth 
before  the  tooth  is  lifted  from  its  cavity.    The  closed  extrac- 


FiG.  97. 
Open   ]\Iolar   Extractor. 

tor  may  be  similarly  curved,  but  owing  to  the  fact  that  when 
they  are  applied  to  the  entire  crown  the  handles  are  wide 
enough  apart  to  pass  the  incisors  between  them,  the  curve 
is  not  as  essential  as  in  the  open  ones. 

THE  ANGULAR  MOLAR-CUTTER. 

The  angular  molar-cutter  is  twenty  inches  long,  and  is 
of  the  same  size  and  pattern  as  the  closed  molar  trimmer. 
Its  jaws  extend  from  the  head  at  an  angle  of  about  forty-five 
degrees,  and  open  in  the  shape  of  a  V  to  fit  the  triangular 
crown  of  the  first  inferior  molar. 

This  instrument  is  used  solely  for  the  purpose  of  beveling 


ANIMAL  DENTISTRY. 


143 


the  first  inferior  molars  and  to  cut  projections  of  nominal 
size  on  the  first  superior  molars.  It  is  a  useful  instrument, 
but  not  an  essential  one.     The  same  work  on  the  superior 


Fig. 
Angular  Molar  Cutter. 

molars  can  be  accomplished  with  the  closed  cutter  and  file, 
and  the  first  inferior  can  be  beveled  with  the  file  to  the  de- 
sired point  without  cutting. 


Fig.  98a. 
Handles  for  Figs.  92,  92a,  94,  9-4a,  95,  97  and  98. 

THE  INCISOR  NIPPERS. 

The  incisor  nippers  is  a  simple  instrument  about  ten 
inches  long,  with  a  screw  joint  to  bring  the  power  nearer  the 
cutting  edge.    It  has  cutting  jaws  which  curve  claw-like  from 


Fig.  99. 
Incisor  Nipper. 

the  head  and  come  in  perfect  apposition  when  the  instru- 
ment is  closed.  The  cutting  surface  should  be  no  less  than 
five-eighths  of  an  inch  wide.  This  instrument  is  used  to 
shorten  the  incisors  and  canines.     It  may  also  be  used  to 


144  ANIMAL  DENTISTRY. 

cut  the  sharp  elongation  at  the  extremity  of  the  first  superior 
molar. 

THE  MOLAR  CROWN   CUTTER. 

The  molar  crown  cutter  or  claw  cutter,  as  it  is  occasion- 
ally called,  answers  the  same  general  description  as  the  open 
molar-cutter,  with  the  exception  that  the  cutting-  jaws  drop 
at  a  right  angle  from  the  head  and  curve  toward  each  other 
like  a  pair  of  claws.  The  jaws  have  a  cutting  edge  of  no  less 
than  three-quarters  of  an  inch,  and  part  three-sixteenths  of 
an  inch  when  the  instrument  is  closed.     They  are  used  to 


Fig.  ioo. 
Molar  Crown  Cutter. 

remove  the  crown  opposing  a  decayed  tooth,  or  that  of  a 
decayed  one  when  extraction  is  not  deemed  advisable. 

THE  MOUTH  SPECULUM. 

The  mouth  speculum  is  indispensable  in  a  dental  prac- 
tice. It  may  consist  of  a  simple  oblong  loop  of  one-quarter 
inch  iron  bar,  a  wooden  gag  to  insert  between  the  molar 
teeth,  or  a  double  bar  that  is  made  to  open  as  wide  as  neces- 
sary with  a  screw.  These  simple  affairs  may  be  made  to 
answer  the  purpose  of  the  more  costly  and  complicated 
ratchet  speculum,  which  has  recently  come  into  quite  general 
use.  The  ratchet  speculum  consists  of  tw^o  cups  to  fit  the 
incisor  arcades,  upper  and  lower,  connected  to  the  ratchet 
mechanism  by  means  of  curved  bars  following  the  line  of  the 
lips  to  a  point  behind  the  commissure  of  the  mouth,  thus 


ANIMAL  DENTISTRY. 


145 


leaving  the  fissure  oris  free  from  obstruction.     They  have 
the  advantage  also  of  opening  the  mouth  to  any  width  de- 

7 


Fig.  ioi. 


sired,  and  the  disadvantages  of  being  none  too  reliable.    The 
ratchet  may  break  or  slip  when  the  jaws  of  a  powerful  horse 


Fig.  102. 

are  set  against  its  strength.  Slipping  of  the  ratchet  is  a  very 
frequent  accident  after  the  catches  have  become  worn  from 
constant  use. 


146 


ANIMAL  DENTISTRY. 


Fig.  I03B. 


i-iG.  103c. 


ANIMAL  DENTISTRY.  ^47 

The  mouth  speculum  is  used  only  for  operation  in  the 
recumbent  position,  and  especially  when  an  animal  is  under 
the  influence  of  an  anaesthetic.  In  the  standing  posture  it 
is  useful  only  to  the  plebe  and  novice.  It  obstructs  the  free 
use  of  larg.e  instruments  in  the  standing  position,  and  is 
unnecessary  for  the  minor  operations. 

THE  TOOTH  CHISEL. 

The  tooth  chisel  is  a  recent  invention,  the  artifice  of  an 
Iowa  veterinarian.  It  consists  of  a  strong  band  of  iron 
shaped  as  a  horseshoe.  At  one  heel  is  a  chisel  inserted  as  a 
lag  screw,  while  on  the  other  heel  is  a  head  to  receive  the 
blows  of  the  hammer.  The  chisel  end  is  passed  into  the 
mouth  while  the  other  heel  is  kept  outside.  Its  object  is  to 
break  or  loosen  teeth  that  cannot  be  grasped  with  forceps. 
It  is  undoubtedly  an  instrument  of  some  value,  especially  in 
the  extraction  of  broken  fangs,  as  it  can  be  equipped  with 
chisels  of  different  dimensions  and  shapes  to  meet  each  re- 
quirement. 

OTHER  INSTRUMENTS. 

The  above  is  a  description  of  the  more  essential  instru- 
ments of  a  dental  outfit  for  a  veterinary  practitioner.  It  is, 
however,  undeniable  that  many  others  might  be  added  to 
the  advantage  of  the  dental  branch  of  veterinary  surgery. 
There  is  room  for  the  addition  of  many  instruments  of  vari- 
ous shapes,  styles  and  patterns  suitable  for  special  purposes. 
For  example,  extractors  for  the  superior  arcades  should  be 
wider  than  those  for  the  inferior;  those  for  the  right  side 
might  be  curved  toward  the  left,  and  those  for  the  left  side 
toward  the  right,  so  as  to  bring  the  instrument  out  of  the 
mouth  at  the  median  line;  those  for  the  last  molars  might  be 
longer  and  have  smaller  heads  and  shorter  jaws,  to  pass 
more  freely  between  the  teeth;  and  finally  all  cutters,  separa- 
tors and  extractors  might  be   made  specially  for  superior, 


14d  ANIMAL  DENTISTRY. 

inferior,  posterior,  anterior,  right  or  left  work  to  the  advan- 
tage of  the  dental  surgeon. 

At  the  present  time  there  is  no  standard  dental  instru- 
ment. Each  manufacturer  and  each  practitioner  has  his 
particular  idea  as  to  what  constitutes  the  appropriate  style 
of  instrument  for  each  particular  purpose,  and  as  a  result 
an  unfortunate  state  of  chaos  exists  in  the  veterinary  dental 
instrument  shop.  This  unfortunate  condition  makes  the 
veterinary  dental  instrument  costly,  as  the  manufacturer 
cannot  reduce  the  cost  by  making  them  in  large  quantities. 

A  change  for  the  better  in  this  connection  will  come  when 
the  dental  operations  are  regarded  as  being  of  sufficient  im- 
portance to  w^arrant  the  adoption  of  standard  methods  of 
operating,  which  in  turn  will  create  a  demand  for  standard 
instruments. 

Trephines,  chisels,  punches,  curettes,  and  the  dissecting 
instruments  used  in  animal  dentistry  are  too  well  known  to 
demand  description  here. 

RESTRAINT. 

Floating,  filing  and  trimming  the  teeth  of  horses  can  be 
accomplished  without  provoking  resistance — enough  to  de- 
mand any  forcible  means  of  restraint.  The  minor  dental 
operations  are  accepted  with  remarkable  complacency  in 
the  great  majority  of  horses.  The  only  necessary  restraint 
is  to  prevent  the  horse  from  backing  away  from  the  operator 
and  from  elevating  the  muzzle  out  of  the  reach  of  the  hands 
and  instruments.  This  is  done  by  backing  the  horse  into  a 
single  stall  and  securing  the  head  at  a  comfortable  height 
on  the  pillar  reins  with  the  dental  halter.  The  ordinary 
leather  halter  is  not  satisfactory  for  this  purpose  because 
one  side  or  the  other  w\\\  press  against  the  cheek  and  pre- 
vent the  free  passage  of  instruments  along  the  teeth. 

The  dental  halter  consists  of  a  leather-covered  iron  loop 


ANIMAL  DENTISTRY. 


149 


fifteen  inches  long  and  nine  inches  wide,  with  a  single  poll 
strap  and  a  ring  on  each  side  for  the  tie  ropes.  The  poll 
strap  is  of  two-inch  heavy  leather  with  numerous  buckle- 
holes  to  make  it  adjustable  to  any  sized  head.  The  tie  ropes 
are  ordinary  half-inch  hemp,  long  enough  to  encircle  the 
pillar  or  to  reach  the  pillars  of  a  stall  of  any  ordinary  width. 
Whenever  the  tie  ropes,  owing  to  the  construction  of  the 
stall,  cannot  be  tied  low  enough  on  the  pillars  to  hold  the 


Fig.  104. 
Horse  Properly  Secured  for  the  Simple  Dental  Operations. 

head  down  to  the  proper  height,  a  third  rope  or  strap  is  tied 
to  the  lower  end  of  the  halter,  passed  between  the  fore  legs 
around  the  withers  and  back  again  between  the  fore  legs  to 
the  halter.  By  this  addition  a  horse  can  be  secured  in  an 
open  room,  field  or  box  stall  with  only  the  assistance  of  one 
person  to  steady  the  head.     (Fig.  105.) 

In   the   absence   of   the   dental    halter   dental   operations 
should  be  performed  with  the  aid  of  an  assistant,  to  hold 


150 


ANIMAL  DExXTlSTRY. 


the  head  with  one  hand  on  the  poll  and  the  other  over  the 
nasal  bones. 


Fig.  105. 

A  Satisfactory  Method  of  Securing  a  Horse  for  Simple  Dental  Operations, 

Without  the  Use  of  Pillar  Reins. 

Major  operations,  i.  e.,  repulsion  of  teeth,  etc.,  and  minor 
operations  upon  vicious  horses,  require  the  recumbent  posi- 


FiG.  105A. 
Lucas'   Dental  Halter. 


tion  and  the  use  of  the   mouth   speculum.     The   operating 
table  is  par  excellence  the  best  restraining  apparatus  for  such 


ANIMAL  DENTISTRY.  151 

operations  because  it  brings  the  head  to  a  comfortable  height 
for   inspection   and   operation. 

Anaesthetics  are  seldom  necessary  to  perform  dental 
operations  and  frequently  they  are  harmful  in  that  they 
favor  the  aspiration  of  blood  and  saliva  into  the  trachea. 
Local  anaesthetics  are  not  applicable  in  any  form  to  the  den- 
tal operations  upon  animals. 

Floating,  filing,  trimming  and  cutting  the  teeth  should  be 
performed  in  the  standing  position.  The  extraction  of  teeth 
may  require  the  recumbent,  but  only  occasionally.  Tre- 
phining the  skull  can  be  performed  in  the  standing  posture 
with  the  aid  of  the  twitch  and  dental  halter,  but  the  repul- 
sion of  teeth  must  never  be  attempted  without  recumbent 
restraint. 

Chiseling,  punching  and  sawing  operations  require  per- 
fect restraint  in  the  recumbent  position. 


CHAPTER  VI. 


DISEASES  AND  IRREGULARITIES  OF  THE  TEETH. 

NECROSIS   OF  THE  TEETH    OF   HERBIVORA. 

Synonyms: — Alveolar-periostitis.  Peridentitis.  Perice- 
mentitis. Pulpitis.  Dentitis :  Caries  (erroneous).  Decayed 
teeth. 


Fig.  io6. 

Molars    Predisposed    to   Decay   by    an    Open    Channel    Through    the    Crusta 

Petrosa  of  the  Infundibula. 

1,  I.     The  infundibula. 

2,  2.     Openings  of  channel  at  table. 

3,  3.  Pulp  cavity.  (In  the  short  [old]  tooth  the  pulp  cavity  is  already 
closed.") 

Definition: — A  total  necrosis  of  one  or  more  molars  of 
herbivorous  animals,  of  inflammatory  origin,  due  to  a  pri- 
mary or  secondary  infective  inflammation  of  the  pulp. 

Etiology: — The   entrance   of  food    into    an    imperfectly 

16i3 


ANIMAL  DENTISTRY.  I53 

closed  infundibulum  is  the  cause  of  more  than  95  per  cent  of 
the  decayed  molars  of  the  horse.  The  crusta  petrosa,  which 
should  hermetically  seal  the  infundibula,  is  found  wanting 
and  thus  leaves  an  entrance  channel  for  infectious  matter. 
The  pulp  is  therefore  the  first  structure  to  be  involved  in 
the  inflammatory  process,  from  which  source  it  traverses 
through  the  apical  foramena  to  the  blood  vessels,  alveola.- 
periosteum  and  bone.  In  rare  cases  the  infectious  matter  is 
admitted  directly  to  the  alveolar  periosteum  through  imper- 
fect gums,  the  space  between  the  teeth,  or  through  the  ex- 
posure of  the  periosteum  while  shedding  the  temporary 
predecessor.     Cystic  tumors  located  directly  upon  the  root, 


Fig.   107. 
Table  View  of  Tooth  Shown  in  Figure  106. 
I,  2.     Openings  of  the  infundibula,  through  which  food  enters  the  tooth. 

atheromatous  degeneration  of  the  radicals  of  the  superior 
dental  artery,  and  external  violence  are  the  determining 
causes  in  a  few  instances.  In  these  latter  circumstances  the 
pulp  is  the  last  structure  to  be  involved  in  the  inflammatory 
process.  Systemic  disturbances,  especially  a  "ricket  dia- 
thesis" induced  by  organic  diseases  or  poor  quality  or  insuf- 
ficient forage  during  the  period  of  growth,  are  predisposing 
influences. 

Pathological  Anatomy: — Pulpitis,  either  primary  or  sec- 
ondary, is  the  basis  from  which  to  study  the  decayed  molar 
of  the  horse.  The  disease  process  begins  with  pulpitis  an^i 
ends  finally  in  self-extraction  of  the  tooth.     Between  these 


154 


ANIMAL    DENTISTRY 


\%  ^ 


^%^'.  w 


Fig.  io8. 
Necrosis  of  an   Inferior   Molar  in   the   Early   Stage,  with   Perforation   from 

Table  to  Root. 


ANIMAL  DENTISTRY 


155 


twc  events  the  following  chain  of  abnormalities  occur:  (i) 
extension  of  the  inflammation  to  the  blood  vessel,  nerves  and 
periosteum ;  (2)  abscess  formation  at  the  root  pointing- 
through  the  peridental  plate  into  the  sinuses  or  surface  of 
the  skull;  (3)  destruction  of  the  blood  supply  of  the  tooth; 
(4)  death,  desiccation  and  splitting  of  the  tooth;  (5)  im- 
paction and  decomposition  of  food  in  the  cavity  between 
the  split  section;  (6)  osteitis  and  necrosis  of  the  alveolar 
border  from  pressure  of  the  split  sections;  (7)  self-extrac- 
tion. The  duration  of  the  process  is  from  three  to  fifteen 
years.  The  above  chain  of  conditions  is,  of  course,  not 
followed  to  the  letter  in  every  instance.     For  example,  an 


Fig.  109. 

intense  periostitis  may  rapidly  loosen  a  tooth  from  its 
cavity  and,  by  admitting  infectious  matter  around  it,  pro- 
duce extensive  osteitis  of  the  jaw.  In  the  young  animals  the 
great  length  of  the  tooth,  and  in  the  inferior  denture, 
gravity,  prevents  the  self-rejection  of  the  tooth  from  its 
cavity,  and  as  a  result  the  loose,  dead  tooth  perpetuates  and 
augments  the  inflammation  and  tumefaction  of  the  sur- 
rounding bones.  This  condition  is  seen  principally  in  the 
inferior  molars  when  the  primary  lesion  has  been  alveolar 
periostitis.      Primary   pulpitis  caused  by  the   open   infund'- 


156 


ANIMAL  DENTISTRY. 


Fig.  no. 
A  Superior  Molar  in  the  Early  Stage  of  Decay. 

A.  The  table. 

I,  2.     Openings   into  the   tooth   admitting  food. 

B,  C.     The  same  tooth  split  longitudinally  to  reveal  its  internal  condi- 


tion. 


ANIMAL  DENTISTRY.  I57 

bulum  in  the  inferior  arcades  frequently  points  to  the 
surface  of  the  jaw  and  constitutes  the  well  known  dental 
fistula  of  the  inferior  maxilla.     (See  Fig.  108.) 

The  incisor  and  canine  teeth  are  not  susceptible  to  the 
condition. 

Diagnosis: — The  molar  tooth  of  the  horse  reaches  the 
advanced  stage  of  decay  unobserved  in  most  instances,  as 
the  incipient  stages  progress  without  clinical  signs  or 
apparent  discomfort  to  the  animal.  The  fetid  breath,  fistula 
or  tumefaction  of  jaws  or  mouth  usually  create  the  first  sus- 
picion of  decayed  teeth.  In  the  absence  of  these  outward 
signs  they  are  only  encountered  accidentally  in  palpations 
of  the  mouth  during  dental  operations.  The  earliest  diag- 
nosis of  a  decayed  molar  is  made  when  the  infective  inflam- 
mation extends  rapidly  into  the  respiratory  mucous  mem- 
brane, before  any  gross  changes  occur  in  the  tooth.  In 
these  cases  the  unilateral  fetid  nasal  discharge  leads  to  an 
examination  for  abnormal  (open)  infundibula  in  one  of  the 
superior  molars.  Anorexia,  rejection  of  partially  masti- 
cated food,  dislike  for  cold  water  or  turning  the  head  to  one 
side  while  masticating,  are  occasional  signs  of  decay  in  the 
incipient  stage,  but  the  diagnosis  must  be  confirmed  by 
better  evidence. 

The  relative  decay  of  the  teeth  of  horses  will  assist  ma- 
terially in  locating  the  offending  member.  The  fourth  su- 
perior molar,  owing  to  its  position  in  the  center  of  the  arcade 
and  its  unstable  neighbors  during  the  second  year  of  colt- 
hood,  is  the  most  common  seat  of  the  disease.  Out  of  a  total 
of  two  hundred  decayed  teeth  observed,  one  hundred  and 
nineteen  were  fourth  superior  molars.  The  fifth  superior, 
the  third  superior  and  fourth  inferior  were  next  in  order, 
while  the  remainder  were  divided  quite  evenly  among  the 
first  superiors,  the  sixth  superior  and  the  remaining  inferior 
molars.     The  second  superior  was  not  found  decayed  until 


158 


ANIMAL  DHXTISTRY. 


the  two  hundred  and  thirty-second  case  was  investigated, 
showinc;-  that  this  tooth  is  not  frequently  decayed. 

Treatment: — (i)  Removal  of  the  tooth;  and,  (2),  re- 
moval of  the  opposing  crown.  Removal  is  the  palpable  duty 
in  dealing  with  the  decayed  tooth  of  the  horse,  but  in  the 


Fig.  III. 


Fig.  112. 


Advanced   Stage  of  Necrosis   in  a   Superior   Molar. 

A.  The  tooth. 

B.  The  table. 

I,   I.     The  opening  through   which   the  tooth  became   infected. 

uncomplicated  case  removal  is  warranted  only  when  it  can 
be  accomplished  in  a  simple  manner  (forcep  extraction). 
When  a  decayed  molar  produces  no  apparent  inconvenience 
and  is  too  short  to  grasp  firmly  with  the  forceps,  removal  of 


ANIMAL   DENTISTRY.  159 

the  opposing  crown  is  ample  remedy  pending  the  develop- 
ment of  serious  complications.  A  decayed  molar,  although 
a  foreign  (dead)  body,  may  become  encysted  in  a  protecting 
wall  and  cause  no  further  trouble.  The  operation  of  remov- 
ing a  tooth  crown  is  accomplished  with  a  claw  cutter.  (Fig. 
lOO.)  The  removal  of  teeth  is  accomplished  by  either  of  the 
following  methods : 

(i)   By  extraction  with  forceps. 

(2)  By  repulsion  with  punch  and  mallet. 

(3)  By  removal  of  the  external  alveolar  plate. 

(4)  By  splitting  with  chisel  and  mallet. 

(i)  EXTRACTION  WITH  FORCEPS. 

Equipment: — Open  molar  extractor,  closed  molar  ex- 
tractor, separating  forceps,  hardwood  fulcra  of  assorted 
sizes,  and  if  operation  is  performed  in  the  recumbent  posi- 
tion, a  mouth  speculum. 

Indications: — Forcep  extraction  should  be  adopted  as  the 
universal  method  to  remove  molars  having  crowns  long 
enough  to  grasp  firmly.  Even  though  trephining  may  be 
necessary  to  reach  the  existing  secondary  condition,  forcep 
extraction  should,  if  possible,  precede  the  trephining. 

Restraint: — Choice  between  the  standing  and  recumbent 
positions  must  be  decided  by  the  probable  complacency  of 
the  patient  and  the  skill  of  the  operator.  For  the  standing 
position  the  horse  is  backed  into  a  single  stall  and  confined 
to  the  pillars  with  the  dental  halter.  The  head  must  be 
brought  downward  within  easy  reach.  If  the  operation  is 
resisted  by  forcible  movements  of  the  jaw  a  mouth  speculum 
may  be  applied.  The  mouth  speculum  should,  however,  be 
avoided  if  possible,  as  it  will  interfere  with  the  free  use  of 
the  instruments.  For  the  recumbent  position  the  patient  is 
placed  in  a  dorso-lateral  attitude  with  the  mouth  speculum 
r.duistf^d  and  the  head  inclining  upward.     Anaesthesia  is  not 


160  ANIMAL   DENTISTRY 

advisable,  owing  to  the  greater  danger  of  blood  flowing  into 
the  trachea. 

Modus  operandi: — The  lirst  retiiiirement  is  to  loosen  the 
tooth.  It  is  safe  to  assert  that  the  tooth  that  cannot  be 
loosened  cannot  be  lifted  from  its  cavity  without  fracture,  or 
injury  to  the  teeth  upon  which  the  fulcrum  is  placed.  The 
loosening  process  is  accomplished  by  wedging  the  molar 
separator  into  the  inderdentia,  first  on  one  side,  then  on 
the  other  until  it  can  be  easily  closed  in  the  spaces.  Tor- 
sion is  then  applied  with  the  extracting  forceps  until  the 
tooth  is  felt  to  be  w^ell  loosened.  Undue  haste  or  the  ap- 
plication of  great  force  must  be  avoided  and  care  must  be 
taken  to  prevent  fracture  in  a  sudden  movement  of  the  head. 
The  extractor  is  now  adjusted  firmly  to  the  crown  and  the 
fulcrum  block  placed  as  near  its  head  as  possible.  Gradual, 
firm  outward  traction  will  readily  bring  the  tooth  from  its 
implantation.  When  the  tooth  is  divided  into  two  or  more 
fragile  segments  the  manipulation  must  be  carefully  exe- 
cuted to  prevent  fracture. 

Accidents:— The  extraction  of  molars  is  not  entirely 
without  danger.  The  possible  misfortunes  are:  (i)  Frac- 
ture of  the  tooth  which  will  necessitate  removal  by  some 
more  complicated  method:  (2)  wounding  the  palatine  artery 
with  the  jaw^  of  the  forceps;  (3)  excessive  hemorrhage  from 
the  dental  artery. 

1.  Fracture  of  the  decayed  tooth  that  is  uncomplicated 
with  secondary  disorders  may  1)e  treated  by  the  simple  re- 
moval of  the  opposing  crowm.  If  there  are  catarrhal  or  fis- 
tulous complications  repulsion  wnll  be  necessary. 

2.  Palatine  hemorrhage  is  serious  and  unless  arrested 
will  endanger  life.  The  accident  occurs  as  a  result  of  the 
horse  chewing  forcibly  upon  the  end  of  the  internal  jaw  of 
the  forcep  wdiile  being  adjusted  to  the  superior  tooth.  As 
soon  as  the  accident  occurs  the  operation  must  cease  and 


ANIMAL  DENTISTRY.  151 

the  mouth  must  be  packed  full  of  cotton,  waste,  oakum  or 
any  other  packing-  material  that  can  be  promptly  furnished. 
When  there  is  delay  in  procuring  a  suitable  packing  the 
finger  must  be  kept  over  the  wound  to  temporarily  arrest  the 
flow  of  blood.  After  the  mouth  is  packed  full  the  jaws  are 
closed  tightly  by  encircling  them  with  a  dozen  wraps  of  cord 
and  the  patient  is  backed  into  a  stall  and  kept  on  the  pillar 
reins  for  five  to  six  hours,  when  the  packing  may  be  safely 
removed. 

3.  Hemorrhage  from  the  dental  artery  may  occasionally 
be  very  profuse,  but  it  is  never  serious.  It  is  arrested  by 
packing  the  cavity  with  wadding  of  cotton,  or  oakum. 


Fig.  113. 
Decayed    Tooth    Due    to    Primary    Alveolar    Periostitis    (Ostertag). 

After-care: — The  tooth  cavity  must  be  wadded  with 
fresh  packing  every  day  for  a  week,  at  which  time  a  careful 
examination  of  the  cavity  must  be  made  to  remove  sequestra 
or  fractured  segments  of  bones,  which  may  delay  prompt 
healing  of  the  wound.  In  two  years  the  opposing  tooth  will 
have  elongated  into  the  vacant  space  and  will  require  trim- 
ming to  the  level  of  its  arcade. 

(2)  REPULSION  OF  TEETH  WITH  PUNCH  AND  MALLET. 

Equipment — Three-quarter-inch  circular  trephine,  one 
inch  circular  trephine,  bone  chisel,  punch,  iron  mallet,  scal- 
pel, artery  forcep,  dissection  forceps,  mouth  speculum,  cu- 
rette, razor,  antiseptics  and  packing  materials. 


162 


ANIMAL  DENTISTRY. 


Indications: — Trephining  the  skull  to  repulse  teeth  is  in- 
dicated when  the  tooth  crown  is  too  short  to  grasp  with  the 
forcep,  and  when  there  is  a  complication  of  fistula  or  catarrh 
of  the  sinuses.  In  secondary  catarrh  of  the  sinuses  with 
more  or  less  accumulation  of  purulent  matter,  trephining  is 


AHP  «   SMITH,  CHICAGO. 


Fig.  114. 
Mallet. 


an  essential  adjunct  to  tooth  extraction,  even  though  the 
extraction  is  accomplished  with  the  forceps.  Trephining  is 
performed  to  evacuate  the  accumulated  secretion  and  to 
admit  the  free  irrigation  of  the  catarrhal  mucous  membrane. 


^3 


SHARP   &   SMITH,   CHICAGO. 

Fig.  114a. 
Straight  Punch. 

as  well  as  for  the  purpose  of  admitting  the  punch  to  repulse 
the  tooth. 

The  following  are  the  molars  that  are  removed  by  repul- 
sion:    Fourth  and  fifth  superior,  sixth  superior  of  old  horses, 


A    OUNN   CO. 


liiiiiuiMililiiiiiiiiiiia 


6HARP   A   SMITH,   CHICAGO. 


Fig.   114b. 
Curved  Punches. 


first,  second,  third  and  fourth  inferior  and  the  fifth  and  sixth 
inferior  when  accompanied  with  considerable  tumefaction  of 
the  jaw. 

Restraint: — The  recumbent  position,  lateral  posture,  af- 


ANIMAL  DENTISTRY.  163 

fected  side  uppermost,  with  a  mouth  specuUim  securely  ad- 
justed, is  the  proper  attitude  for  the  repulsion  of  teeth.  The 
standing  posture  is  never  satisfactory.  The  operating  table 
is  par  excellence  the  best  method,  as  the  head  can  be  more 
firmly  secured  than  with  the  casting  harness.  General 
anaesthesia  is  sometimes  harmful,  as  in  the  unconscious 
state  blood  readily  finds  its  way  into  the  lungs. 

Location  of  the  openings: — The   opening  in    the    skull 
must  be  situated  so    that    the    punch  can  be  placed  on  a 


Fig.  115. 

Cut  Representing  the  8  Teeth  Which  Can  Be  Repulsed  and  the  Location  of 

the  Opening  for  Each. 

Straight  line  with  the  long  axis  of  the  tooth.  (See  Fig,  116.) 
The  transverse  range  will  vary  slightly  with  the  age  of  the 
horse.  In  the  young  horse  well  toward  the  median  line  of  the 
head  and  in  the  old  one  nearer  the  maxillary  spine.  The  lon- 
gitudinal range  will  vary  according  to  the  tooth  to  be  re- 
pulsed, the  fourth,  fifth  or  sixth.  The  exact  seat  is  deter- 
mined after  the  animal  is  secured  and  otherwise  prepared  for 
the  operation.    The  hand  is  placed  into  the  mouth  and  a 


154  ANIMAL    DENTISTRY. 

finger  pressed  against  the  cheek  opposite  the  decayed  tooth, 
and  from  the  bulge  ihns  made  in  the  cheek  externally  a 
measurement  is  made  upward  to  a  point  indicated  l)y  the 
animal's  age.  In  the  voung  horse  a  slight  variation  must  be 
made  for  the  backward  direction  of  the  fifth  molar.  The  sixth 
molar  in  young  animals  is  rellected  backward  l:)eneath  the 
eye  and  cannot  be  satisfactorily  repulsed. 

For  the  inferior  molars  the  openings  are  made  at  the 
very  border  of  the  jaw  in  every  case  except  for  the  fifth  and 
sixth,  in  wdiich  instance  it  is  made  upon  the  most  prominent 
part  of  the  tumefaction  caused  by  the  diseased  process.  For 
the  third,  fourth  and  fifth  inferior  molars,  due  allowance 
must  be  made  for  the  marked  backward  direction  of  their 
fangs.     (See  Fig.  115.) 

The  openings  must  be  made  with  due  deference  for  the 
following  important   structures : 
(i)   Steno's  duct. 

(2)  Lachrymal  canal. 

(3)  Glossofacial  artery  and  vein. 

(4)  Superior  dental  canal  and  contents. 

(5)  Inferior  dental  canal  and  contents. 

(6)  Superior  maxillary  division  of  the  trifacial  nerve 

near  its  exit  from  the  skull. 
In  the  repulsion  of  the  superior  teeth  complicated  with 
catarrh  a  single  additional  opening  is  made  to  drain  the  fron- 
tal sinus  and  to  give  free  access  to  the  maxillary  sinus,  as 
well  as  to  drain  the  frontal  sinus  into  the  nasal  fossa.  This 
opening  is  located  in  an  oblique  direction  downward  and  in- 
ward four  centimeters  from   the  nasal   canthus.      (See   Fig. 

151) 

Opening  the  Skull: — This  step  of  the  operation  requires 

the  consecutive  dissection  of  (i)  the  skin,  (2)  the  subcutane- 
ous areolar  tissue  and  muscles,  (3)  the  periosteum,  (4)  the 
bone,  and  (5)  the  mucous  membrane. 


ANIMAL   DENTISTRY. 


165 


Repulsion  of  the  Tooth: — The  right  hand  is  placed  in  the 
mouth  with  a  finger  pressing  firmly  against  the  tooth  while 
the  left  hand  directs  the  punch.  The  assistant  is  then  di- 
rected to  strike  firmly  with  the  mallet  until  the  impression 
of  the  blow  is  felt  by  the  finger  against  the  tooth,  and  then 
forcibly  until  it  is  driven  from  its  cavity.  Failure  to  trans- 
mit an  impression  into  the  mouth  is  an  indication  that  the 
punch  is  not  advantageously  located. 


Fig.  ii6. 
Cut   Representing   the    Proper   and   the    Improper    Methods   of    Placing   the 
Punch  to  a  Tooth  to  Be  Repulsed. 
A.     Proper  method;  punch  on  a  straight  line  with  tooth. 
R.     Improper    method. 

Aftercare: — As  soon  as  the  tooth  is  removed  the  patient 
is  made  to  resume  the  standing  position.  The  frontal  sinus, 
maxillary  sinus  and  nasal  fossa  are  then  freely  opened  into 
each  other  by  breaking  down  the  fragile  septa  separating 
them.  The  cavities  are  then  emptied,  irrigated,  and  wadded 
with  antiseptic  cotton.     Daily  irrigation  with  3  per  cent  zinc 


166  ANIMAL   DENTISTRY. 

sulphate  solution  and  renewal  of  the  wadding-  for  two  weeks 
or  until  the  discharge  ceases,  is  the  necessary  after-care. 

Sequelae: — (i)  Alveolo-nasal  fistula,  (2)  persistence  of 
the  catarrh  and  reaccuniulation  of  pus  in  the  sinuses,  (3)  per- 
sistence of  the  opening  (chronic  nasal  fistula),  (4)  sep- 
ticaemia, (5)  deglutition  pneumonia. 

1.  Alveolo-nasal  fistula,  allowing  the  free  passage  of  food 
from  the  mouth  to  the  nasal  cavities  or  sinuses  is  a  common 
result  of  repulsion  of  teeth  of  the  upper  jaw  in  aged  horses 
or  from  allowing  food  to  pack  tightly  into  the  tooth  cavity 
before  it  has  had  an  opportunity  to  close.  They  also  occur 
spontaneously  in  decay  of  the  first  molar  or  from  extrac- 
tion with  the  forceps.  In  the  old  horse  they  are  prevented 
by  the  application  of  a  gutta  percha  plug  between  the  crowns 
of  the  teeth  bounding  the  vacant  cavity  and  in  the  young 
horse  by  preventing  the  packing  of  food  into  the  cavity.  A 
tight  wadding  placed  between  the  crowns  after  repulsion 
will  not  interfere  with  the  healing  and  closure  of  the  cavity. 
The  treatment  of  the  chronic  dento-nasal  fistula  consists  of 
removing  the  impacted  food  from  the  nasal  cavity  or  sinus 
by  trephining  and  the  application  of  a  permanent  plug  of 
gutta  percha  into  the  channel.  To  prevent  further  packing 
against  the  plug  the  opposing  crown  is  removed.  For  fistula 
of  the  first  molar  the  surgeon  may  choose  between  this 
method  and  the  obliteration  of  the  channel  by  removing  the 
external  alveolar  plate  and  the  opposing  crown. 

2.  Persistence  of  the  catarrh  will  demand  a  second  opera- 
ation  and  more  precise  after-care.  This  sequel  is  the  result 
of  failure  to  properly  drain  the  sinuses  into  the  nasal  cavity, 
or  careless  and  dilatory  irrigation. 

3.  Dental  fistula  or  chronic  sinuses  of  the  lower  jaw, 
have  their  origin  in  bone  necrosis,  failure  to  remove  the 
entire  tooth  or  the  proper  tooth.  Reopening  of  the  wound 
and  removal  of  the  insulting  agent  is  the  remedy. 


ANIMAL  DENTISTRY. 


167 


4.  Septicaemia  is  the  result  of  improper  method  of  op- 
erating, the  use  of  septic  irrigation  fluids,  or  neglect  to  irri- 
gate properly. 

5.  Deglutition  pneumonia  results  from  the  flow  of  blood, 
antiseptic  fluid  or  pus  into  the  lower  air  passages  during  the 
operation.     It  is  caused  either  from  anaesthesia  or  the  use 


Fig.  117. 

Molar  Denture  of  a  Young  Horse,  in  Which  Extraction  is  Difficult,  Owing 

to  the  Deep  Implantation. 

of  the  speculum,  which  prevents  deglutition  of  fluids  which 
fall  into  the  pharynx. 

^3)  REMOVAL  OF  THE  EXTERNAL  ALVEOLAR  PLATE. 

(Williams'  Operation) . 
Equipment: — Bone    chisel,    narrow-blade    saw,     scalpel, 
dissecting   forceps,    artery   forceps,    mouth    speculum,    ant'.- 
septics,  and  mouth  gag. 


168 


ANIMAL   DENTISTRY 


Fig.  1 1 8. 
jMolar  Denture  of  ^Mature  Middle  Aged  Horse. 


Fig.  119. 

Molar  Denture   of  an   Aged   Horse,   in    Which    Extraction    is    Easy,    Owing 

to  the   Shallow    Implantation. 


ANIMAL    DENTISTRY. 


169 


Restraint: — Lateral  recumbent  position,  under  chloro- 
form anaesthesia  or  local  cocainization,  preferably  the 
former. 

Indications: — This  operation  should  be  adopted  univer- 
sally for  the  removal  of  the  first,  second  and  third  superior 
molars.  Applied  to  the  fourth  or  fifth  superior  molars  a  de- 
formity of  the  face  results  from  the  removal  of  the  extremity 
of  the   maxillary  spine,   and  besides   it  has   no  advantages 


Fig.  120. 
Chisel. 


Fig.  121. 
Saw. 


Fig.    I2IA. 
Mouth    Gag. 
The  Most  Appropriate   Speculum  for 
Williams'   Operation. 


over  repulsion  for  these  teeth.  It  may  also  be  applied  to 
removal  of  the  first,  second  and  third  inferior  molars,  but  in 
these  it  has  no  special  advantages  over  repulsion.  For  the 
first  three  superior  molars,  especially  the  third  and  second, 
the  operation  is  almost  indispensable,  and  it  out-classes  re- 
pulsion because  the  almost  perpendicular  wall  of  the  skull  at 
this  point  prevents  the  placing  of  the  punch  on  a  straight 
line  with  the  tooth,  and  finally,  in  repulsing  the  third  tooth 
the  opening,  if  properly  placed,  necessitates  division  of  the 


170  ANIMAL   DENTISTRY. 

superior  maxillary  branch  of  the  fifth  cranial  nerve  near  its 
exit  from  the  infraorbital  foramen. 

ist  step. — Clip,  shave  and  disinfect  a  liberal  space  at  seat 
of  operation. 

2nd  step. — }klakc  a  lons^itiidinal  (parallel  to  long-  axis  of 
skull)  incision  two  inches  long-  through  the  skin  and  muscles 
directly  over  the  root  of  the  affected  tooth. 

3rd  step. — Separate  the  soft  tissues  from  the  bone  from 
the  incision  to  the  gingival  margin  in  the  mouth. 

4th  step. — Saw  through  the  skull  along  the  interdentium 
on  each  side  of  the  tooth ;  then  chisel  the  bone  flap  loose 
superiorly. 

5th  step. — Pry  the  released  plate  of  bone  loose  with  the 
chisel,  and  remove  with  the  forceps. 

6th  step. — Release  and  elevate  the  tooth  by  prying  with 
chisel  and  mallet. 

7th  step. — Close  incision  with  sutures  and  arrest  hem- 
orrhage by  packing  from  within  the  mouth. 

8th  step. — Remove  crown  of  opposing  molar  to  prevent 
packing  of  food  into  the  cavity. 

After-care. — Remove  the  packing  in  twenty-four  hours. 
Irrigate  daily  with  mild  antiseptic  solution,  and  keep  in- 
cision well  protected  with  clay  paste. 

(4)     REMOVAL  OF  TEETH  BY  SPLITTING  WITH  CHISEL. 

This  operation  is  indicated  for  the  removal  of  the  first 
superior  or  first  inferior  molars  when  the  crowns  cannot  be 
held  in  the  forceps.  It  is  performed  in  the  recumbent  posi- 
tion with  the  aid  of  a  mouth  speculum.  Recently  an  inven- 
tor has  placed  upon  the  market  a  tooth  chisel  shaped  like 
a  horseshoe,  that  can  be  used  to  chisel  any  molar  tooth. 
Such  an  instrument  is  of  service  in  splitting  and  removing 
badly  diseased  fangs  when  major  methods  are  unwarranted, 
and  to  serve  as  a  wedge  to  dislodge  the  remaining  fangs  of 


ANIMAL   DENTISTRY. 


171 


teeth   accidentally  fractured   in   attempts   to    extract    them 
with  the  forceps. 

EXTRACTION  OF  THE  INCISORS. 
Owing  to  the  deep  implantation  and  curvature  of  the 
fang,  the  incisors  cannot  be  readily  extracted  by  any  ordi- 
nary method,  except  in  extreme  old  age,  when  the  fang  has 
become  shortened.     During  youth  and  middle  age  their  ex- 


FlG.    122. 

Cut  Showing  the  Great  Length  and  Curvature  of  the  Incisors,  th?,t  Prevents 

Forcep  Extraction. 

traction  can  only  be  accomplished  by  removal  of  the  anterior 
alveolar  plate  and  then  prying  the  tooth  out  with  a  chisel  or 
elevator.  The  subject  is  placed  in  the  recumbent  position 
and  the  mouth  tied  shut  with  several  wraps  of  sash  cord 
around  the  muzzle.  With  knife  and  forceps  the  mucous 
membrane  and  gums  are  removed  over  the  fang,  the  peri- 
osteum is  scraped  off  with  a  curette  and  the  bone  removed 


172  ANIMAL  DENTISTRY. 

witli  a  chisel.  When  the  fang  is  exposed  througliont  its 
entire  len,^th  the  chisel  is  (h'ivcn  under  the  tooth  and  it  is 
pried  out. 

The  incisors  of  the  solipeds  and  ruminants  are  seldom 
decayed  to  tlie  point  requiring-  extraction.  Longitudinal 
fractures  from  falls  or  l)lo\vs  may  loosen  a  part  of  an  incisor 
and  provoke  decay  of  the  remaining  portion,  and  occasion- 
ally a  persistent  temporary  with  a  long  fang  may  demand 
attention  to  improve  the  appearance  of  the  mouth,  but  aside 
from  these  instances  extraction  is  seldom  required.  The 
temporary  incisors  are  frequently  extracted  to  give  the  horse 
the  appearance  of  l)eing  one  year  older,  or  when  the  shed- 
ding is  delayed  beyond  the  usual  period. 

EXTRACTION  OF  THE  CANINES  OF  HORSES. 

The  deep,  curved  alveolar  cavity  of  the  horse's  canines, 
like  the  incisors,  prevents  forcep-extraction,  in  the  young 
animal.  They  are  removed  only  in  the  recumbent  posture, 
by  the  removal  of  the  external  alveolar  plate  and  prying 
v^ith  the  chisel  as  in  the  case  of  the  incisor. 

The  canines  are  seldom  decayed  except  from  pulpitis  and 
periostitis  following  injuries  to  the  tooth  or  jaw. 

CARIES. 

Synonyms: — Caries  dentium,  decayed  teeth,  ulceration 
of  teeth.  (It  must  not  be  confounded  with  alveolar  perios- 
titis of  herbivora). 

Definition: — Caries  signifies  rotteness.  As  a  diseased 
process  it  might  be  appropriately  defined  as  a  biochemic  de- 
composition of  the  dentinal  substance  originating  at  one  or 
more  points  of  a  tooth.  It  might  also  be  defined  as  a  pro- 
gressive disintegration  of  a  tooth's  substance,  penetrating 
from  the  surface  toward  the  center. 

Etiology: — The  exciting  cause  of  caries  is  erosion  or  frac- 


ANIMAL  DENTISTRY.  173 

tiire  of  the  enamel  covering,  through  which  channel  acids 
and  micro-organisms  gain  access  to  the  sensitive  parts  of  the 
tooth.  The  acids  dissolve  the  calcium  salts  as  the  micro- 
organisms decompose  the  organic  material,  producing  con- 
jointly a  gradual  gnawing  away  of  the  substance.  The 
progress  of  disintegration  is  frequently  arrested  by  the  for- 
mation of  a  protecting  wall  around  the  cavity  not  unlike  the 
pyogenic  wall  of  an  abscess  of  the  soft  tissues.  This  process 
is  due  to  the  calcification  of  the  intra-tubular  substance  of 
the  dentine.  In  other  events  it  progresses  until  the  entire 
tooth  has  become  destroyed. 

The  acids  responsible  for  the  dissolution  of  the  cal- 
careous matter  of  the  tooth  reach  the  teeth  by  being  in- 
gested as  such,  or  by  the  transformation  of  food  products 
into  acid  substances.  The  micro-organisms  are  the  putrefac- 
tive parasites  which  normally  inhabit  the  mouth  and  which 
only  become  pathogenic  at  the  proper  opportunity.  Efforts 
to  isolate  a  specific  organism  have  thus  far  failed. 

The  predisposing  causes  are  numerous.  Impairment  of 
the  general  health  during  the  period  of  dental  evolution, 
rickets,  pregnancy,  irregularities  of  the  arcades,  meat  diet 
and  uncleanliness  of  the  mouth  are  the  chief  conditions  re- 
sponsible for  the  disease. 

Susceptible  animals.  In  man  caries  is  the  most  common 
of  all  pathological  conditions.  Few  mature  human  beings 
escape  its  ravages  upon  the  teeth.  It  is  essentially  a  disease 
of  mature  life,  although  when  the  predisposing  causes  are 
legion  even  the  temporary  teeth  may  be  attacked  to  a  re- 
markable extent.  In  the  domestic  animals  it  is  observed 
occasionally  in  the  old  dog,  hog  and  cat.  Solipeds  and 
ruminants  are  comparatively  free  from  caries.  In  these  ani- 
mals decay  of  the  teeth  takes  the  form  of  an  inflammatory 
disintegration.  (Necrosis,  see  page  152).  In  rare  cases  the 
dissolution  of  the  herbivorous  tooth  may  undergo  a  disin- 


174 


ANIMAL   DENTISTRY. 


tegrating  process  which  neither  resembles  caries  (the  non- 
inflammatory condition)  nor  necrosis  (the  inflammatory- 
condition),  and  as  a  result  leaves  the  impression  that  caries 
is  existent  in  the  her1)ivorous  animals.  Caries,  the  disease 
of  human  teeth  having  its  uniform  cause,  course  and  termi- 
nation, is  not  seen  in  the  herbivora,  and  the  short  lives  of 
the  other  domestic  animals  places  the  disease  among  the 
rare  disorders  in  veterinary  practice. 

Treatment: — The  carious  tooth  of  dogs,  cats  and  pigs 
is  treated  by  prompt  extraction.  Leveling,  burnishing  and 
stopping  the  carious  cavity,  which  constitutes  the  universal 
treatment  of  the  disease  in  the  human  tooth  is  an  attainment 
not  expected  of  a  veterinarian  at  the  present  time,  and  the 


Fig.  I22A. 
White's  Dog  Speculum. 

rarity  of  the  indications  w^ill  doubtless  always  prevent  its 
introduction  into  the  veterinary  college  curriculum. 


EXTRACTION  OF  THE  TEETH  OF  DOGS. 

When  the  teeth  of  carnivora  are  loosened  from  disease 
their  extraction  is  easily  accomplished  wnth  the  forceps,  but 
when  the  implantation  is  not  disturbed  they  can  seldom  be 
extracted  without  fracture.  The  canines,  especially,  are 
firmly  imbedded  into  a  curved  cavity  and  will  defeat  any 
ordinary  method  of  removal. 

The  extraction  of  the  teeth  of  dogs  is  best  accomplished 
by  first  disturbing  the  implantation  with  a  cutting  bone  for- 
ceps along  each  side  of  the  fang  before  applying  the  ex- 
tracting forceps.     The  molars,  canines  and  incisors  may  be 


ANIMAL  DENTISTRY.  I75 

treated  in  the  same  manner.  A  handy  method  of  securing 
a  dog  for  tooth  extraction  is  to  tie  a  piece  of  tape  around 
each  jaw  behind  the  canine  teeth,  then  an  assistant  stands 
astride  of  the  dog,  pinches  the  head  taut  between  his  knees 
and  holds  the  mouth  open  with  the  tape  as  the  operator 
appHes  the  instruments.  This  method  is  even  preferable  to 
the  operating  table,  which  places  the  mouth  in  an  awkward 
position  for  extraction. 

ABNORMAL  ERUPTIONS  OF  THE  TEETH. 

Shedding  of  the  incisor  teeth  depends  upon  "growth  pres- 
sure" from  the  permanent  successors.     If  the  forming  tooth 


Fig.  I22B. 
Baker's   Dog    Speculum. 

does  not  adjust  itself  directly  upon  the  apex  of  the  temporary 
fang  the  latter  may  remain  wedged  between  two  contiguous 
teeth  through  life.  If  this  same  condition  exists  in  all  the 
incisors  the  result  is  a  complete  double  set  of  incisors. 

When  such  abnormalities  are  observed  early  enough  the 
temporary  teeth  should  be  extracted.  In  later  years  they  are 
best  left  undisturbed. 

The  canine  teeth  frequently  remain  covered  with  the 
gums  for  several  years  after  their  usual  period  of  eruption, 
and  thus  cause  a  more  or  less  painful  irritation  to  the  mouth. 
The  condition  is  observed  most  frequently  in  the  six  and 
seven-year-old  driving  horse  by  the  resistance  such  animals 


176 


ANIMAL   DEXTISTRV. 


offer  to  llic  adjuslnicnt  of  llic  liridlc  or  by  sliakiiu;-  llic  head 
while  driving-.  The  conchtion  is  met  by  lancing  the  gums, 
which  is  best  done  \\ith  tlie  CLir\'ed  scissors. 

1'lic  molar  teeth  having  temporary  predecessors,  the  first, 
second  and  third,  for  obscu-rc  reasons  occasionally  cease  to 
grow  sufficiently  to  force  out  the  temporary  ones,  and  as 
the  latter  are  not  sufficiently  stable  to  perform  the  function 
of  mastication,  the  whole  area  becomes  infected  and  the 
result  is  a  large  tumefaction  of  the  jaw.  When  the  tem- 
porary teeth  are  extracted  the  dead  undeveloped  permanent 


Fig.  123. 
A   Persisting  Temporary   Tooth   Due   to   Faulty   Eruption   of   Its    Permanent 

Successor. 

ones  are  found  lying-  loosely  beneath  them.  This  condition 
is  found  chiefly  on  the  lower  jaw.  The  condition  will  always 
respond  promptly  to  the  removal  of  both  the  temporary  and 
permanent  teeth  involved  in  the  process.  One,  two  or  all 
three  teeth  may  be  affected. 

On  the  superior  jaw  osteoma  of  the  maxilla  over  the 
third,  second  or  first  molars  is  often  produced  by  backward 
pressure  of  the  permanent  teeth  when  their  downward 
growth  is  blocked  by  a  wedged  temporary  tooth. 

These  conditions  occur  in  young  horses  from  two  to  five 
years  old  and  are  often  mistaken  for  decayed  teeth  or  tumors 


ANIMAL  DENTISTRY.  I77 

of  more  serious  import.  They  may  be  unilateral  or  bilateral. 
If  the  temporary  tooth  is  already  shed  the  condition  must 
be  treated  on  the  expectant  plan.  Blisters  and  time  will 
remove  the  condition  in  from  two  months  to  one  year.  They 
seldom  persist  long-er.  Removal  of  the  greater  portion  of 
the  tumor  by  trephining  it  from  apex  to  base  with  a  large 
trephine  will  hurry  the  recovery,  but  there  is  some  danger 
of  producing  a  chronic  fistula  that  is  difficult  to  heal. 

DENTAL  CYSTS. 

Dental  cysts  is  the  name  we  apply  to  cystic  growths  oc- 
curring along  the  course  of  the  artery  supplying  the  tooth. 
They  vary  in  size  from  small  sacs  the  size  of  a  marble  to 
growths  that  entirely  fill  the  sinuses  and  even  cause  bulging 
of  the  facial  bones.  They  are  probably  the  result  of  athero- 
matous degeneration  in  the  wall  of  the  nutrient  artery  of  the 
molar  tooth.  They  frequently  become  infected  and  cause 
alveolar-periostitis,  chronic  nasal  catarrh,  or  both.  Regard- 
less of  size,  they  completely  destroy  the  nutrition  of  the 
tooth  by  obliterating  the  nutrient  vessel,  and  after  they  ex- 
pel their  contents  the  dead  tooth,  entirely  stripped  of  its 
peridental  covering,  is  left  projecting  into  the  sinus.  During 
the  early  stages  of  the  resulting  catarrh  a  diagnosis  of  the 
real  condition,  before  operation,  is  impossible.  A  tooth  so 
affected  will  finally  become  loosened  and  thereby  for  the 
first  time  reveal  the  true  cause  of  the  catarrh.  In  rare  in- 
stances the  projecting  root  becomes  encysted  in  a  new  mass 
of  fibrous  tissue  and  remains  intact  through  life.  The  dental 
cyst  explains  the  nature  of  the  cause  of  some  of  these  ob- 
scure cases  of  chronic  nasal  catarrh  which  are  described  as 
primary.  When  recognized  these  cysts  are  treated  by  re- 
pulsion of  the  affected  tooth,  which  is  located  by  palpation 
or  inspection  after  the  skull  has  been  trephined.    The  disease 


178 


ANIMAL   DENTISTRY. 


is  confined  to  the  fourth,  lifth  and  sixth  superior  molars.,  and 
it  originates  in  the  young  animal. 

ODONTOMATA. 

Synonym: — Tooth  tumors. 

Definition: — A    dentinal     growth     of     non-inflammatory 
origin,  occurring  on  the  fangs  of  the  teeth. 

Etiology: — The  cause  of  these  growths  is  obscure.     Thev 


f 

i 

[ 

II 

Fig.  124.  Fig.  125. 

A  Large  Odontoma  of  the  6th  Su-        Odontomata  of  the  3rd  and  4th   Su- 
perior Molar.  perior  Molars. 

are  probably  the  result  of  some  perversion  of  their  foetal 
evolution. 

Symptoms: — The  odontoma  may  exist  unobserved  until 
attempt  is  made  to  extract  the  tooth  to  which  it  is  attached. 
The  tooth  will  be  easily  loosened,  but  in  spite  of  all  efforts 
it  cannot  be  lifted  from  its  cavity.  There  is  usually  a  slight 
tumefaction  of  the  skull  over  its  fang.  In  the  superior  ar- 
cades and  on  the  posterior  teeth  of  the  inferior  arcades  they 


ANIMAL  DENTISTRY. 


179 


are  occasionally  determined  by  monstrosity  of  the  crown. 
The  crown  will  be  found  expanded  in  all  directions,  often 
extending  well  toward  the  median  line  of  the  palate.  They 
may  weigh  upward  to  five  or  six  pounds. 

Treatment: — The  odontoma  causing  no  inconvenience  is 
left  undisturbed.  When  ablation  becomes  necessary  through 
decay  of  the  tooth  or  infection  of  the  surrounding  perios- 


FiG.  126. 

An  Odontoma  of  the  2nd  Inferior  Molar  Weighing  5  Pounds.     The  White 

Portion  Is  the  Table  Surface  of  the  Original  Tooth. 

teum,  they  are  removed  by  first  trephining  and  chiseling  the 
skull  over  the  most  prominent  part  of  the  tumor,  and  then 
dividing  it  into  sections  until  repulsion  is  possible. 

BRACHYGNATHISM. 


Synonyms — Parrot   mouth.      Receding    jaw.     Receding 


chin. 


180 


ANIMAL   DENTISTRY. 


Definition — A  congenital  deforniity  in  which   the   supe- 
rior incisors  overlap  the  inferior. 

Etiology — A  congenital  deforniity  of  obscure  cause.  The 
deformity  consists  of  a  deficiency  in  the  proper  length  of  the 
inferior  maxillary,  or  an  abnormal  elongation  of  the  pre- 
maxilla. 

Symptoms — Overlapping  of  the  inferior  incisor  by  the 
superior  ones  with  more  or  less  elongation  of  the  first  supe- 
rior and  sixth  inferior  molars.     The  condition  becomes  more 


Fig.  127. 
A  Typical  Case  of  Brachygnathism. 

and  more  aggravated  wnth  age.  As  the  molars  wear  away 
the  inferior  incisors  reach  the  palate  behind  the  superior  in- 
cisors. Nature,  however,  seems  to  meet  the  condition  by 
hardening  of  the  palate  and  rounding  the  premaxilla  so  as  to 
accommodate  the  gradual  transgression  of  the  inferior  in- 
cisors. There  will  be  difficulty  in  the  prehension  of  attached 
food,  and  the  animal  will  be  difficult  to  keep  in  good  condi- 
tion. 

Treatment — Parrot  mouth  is  a  defect  for  which  horses 


ANIMAL  DENTISTRY. 


181 


must  be  condemned  in  an  inspection  for  soundness.  The 
inferior  incisors  must  be  shortened  by  filing  from  time  to 
time,  and  the  elongated  molars  must  be  trimmed  to  the  level 
of  the  other  teeth.  Shortening  the  superior  incisor  is  useless 
and  inadvisable.  Filing  or  cutting  a  considerable  portion  of 
either  the  inferior  or  superior  incisors  is  harmful,  as  these 
teeth,  having  never  been  subjected  to  the  influence  of  wear. 


Fig.  128. 
A  Typical   Case  of   Prognathism. 

are  sensitive  to  the  very  tables,  and  will  bleed  if  much  of  the 
crown  is  removed. 

PROGNATHISM. 

Synonyms — Undershot.       Prominent     jaw.      Prominent 

chin. 

Definition — A  congenital  deformity  in  which  the  inferior 
incisors  overlap  the  superior.     The  deformity  consists  of  a 


182 


ANIMAL   DENTISTRY. 


deficiency  in  the  proper  leni^th  of  the  preniaxilla  or  an  elon- 
gation  of   the    inferior   maxilla. 

Symptoms — Prognathism  exists  most  fre(|uently  in  dogs 
in  which  animals  it  is  characteristic  of  certain  breeds.  It  is, 
however,  occasionally  encountered  in  the  horse,  the  molars 
sharing  the  abnormality. 


^~d- 


Fig.  129. 
A  Typical   Case  of  Parvignathistn    (Ostertag). 
A,  B.     The  beveled  molars. 
C.     1st  inferior  molar  absent. 

Treatment — In  the  dog,  none.  In  the  horse  the  superior 
incisor  crowns  are  shortened  from  time  to  time  by  filing  and 
the  molars  are  kept  level. 

PARVIGNATHISM. 

Synonyms — Scissor  mouth.      Beveling  of  the   molars. 
Definition — A  congenital  deformity  consisting  of  a  de- 
ficiency in  the  proper  width  of  the  lower  jaw,  or  more  prop- 


ANIMAL    DENTISTRY. 


183 


Fig.  130. 
Parvignathism,  with  Beveling  of  the  Buccal  Surface  of  the  Inferior  Molars. 


f '      J 


Fig.  131. 

Samples  of  Beveled  Molars  Removed. 


184  ANIMAL  DENTISTRY. 

erly  s',)eaking'.  a  (leficicncy  in  the  proper  distance  between 
tlic  inferior  arcades,  cansinj^  a  l)eve]ing'  of  the  molars. 

Symptoms — 'Jdie  hevehng'  is  usually  conhned  to  l^iit  one 
side.  The  molars  of  one  superior  arcade  become  beveled 
from  without  inward  entirely  obstructing  the  lateral  motion 
toward  the  afifected  side.  The  condition  is  frequently  com- 
plicated with  decay  of  one  or  more  molars,  and  mastication 
is  almost  impossible  in  the  advanced  stage.  Parvignathism 
is  one  of  the  most  serious  irregularities  of  the  horse's  mouth. 

Treatment — With  the  large  lever  cutter  (Fig.  92),  the 
beveled  crowns  of  the  entire  superior  and  inferior  arcades 
must  be  trimmed  almost  to  the  level  of  the  gums,  beginning 
with  the  first  molars,  and  the  decayed  teeth,  if  any,  must  be 
removed.  This  treatment,  while  placing  one-half  of  all  the 
molars  entirely  "out  of  commission,"  will  be  met  by  prompt 
relief  to  the  patient. 

PROJECTIONS    ON    THE    FIRST    SUPERIOR    AND 
SIXTH  INFERIOR  MOLARS. 

Definition — A  universal  irregularity  existing  in  the  molar 
arcades  of  all  mature  horses,  consisting  of  sharpened  points 
of  enamel  at  the  anterior  end  of  the  superior  arcades  and  the 
posterior  end  of  the  inferior  arcades. 

Etiology — The  aggravated  forms  due  to  such  gross  de- 
formities as  brachygnathism  or  congenital  or  acquired  de- 
ficiency in  the  proper  length  of  one  or  both  arcades  are  not 
included  in  this  category.  The  large  elongations  occurring 
at  the  extremities  in  either  of  the  molar  arcades  are  usually 
due  to  a  deficiency  in  the  length  of  the  opposing  arcade, 
but  in  this  minor  irregularity  the  lengths  of  the  arcade? 
are  equal.  These  points  are  caused  by  the  position  of  the 
muscles  of  mastication.  The  fixed  attachments  of  all  the 
muscles  of  mastication  except  the  masseter    and    external 


ANIMAL  DENTISTRY.  185 

pterygoid  are  located  posteriorly,  and  therefore  lift  the  jaw 
sli.sfhtly  backward  at  each  contraction.  The  absence  of  any 
muscle  with  an  anterior  fixed  attachment  to  antagonize  this 
backward  traction  is  the  cause  of  these  universal  irregulari- 
ties. The  masseter's  influence  in  that  connection  is  insuf- 
ficient. 

Treatment — In  driving  horses  the  anterior  ones  wound 
the  mucosa  and  require  filing. 

PROJECTIONS  ON  THE  SUPERIOR  CORNERS. 

(See  Fig.  y2.) 
At  about  the  age  of  seven  years  there  appears  on  the 
superior  corner  incisor  a  sharp  enamel  point  which  in  most 
instances  will  disappear  during  the  three  ensuing  years. 
This  irregularity  is  due  to  a  congenital  deficiency  in  the  di- 
mension of  the  inferior  corners.  They  disappear  under  the 
influence  cited  in  the  preceding  paragraph,  i.  e.,  the  back- 
ward traction  by  the  muscles  of  mastication. 

ACQUIRED  ELONGATION  OF  THE  MOLARS. 

Definition — Projections  of  the  molars  into  vacant  cavi- 
ties on  the  opposing  arcades. 

Etiology — The  common  cause  of  elongation  of  this  vari- 
ety is  the  loss  of  a  molar  by  extraction.  They  occur  also 
from  the  decayed  molar  that  ofifers  no  adequate  wearing 
surface  for  its  opponent.  Occasionally  in  old  age  the  molars 
become  excavated  from  a  defect  in  texture. 

Symptoms — Defective  mastication,  rejection  of  food,  ac- 
cumulation of  food  beneath  the  buccinator  and  tumefaction 
of  the  jaw  are  the  signs  usually  directing  the  attention  to 
such  teeth.  Palpation  and  inspection  will  reveal  a  large 
tuberous  projection  involving  one  or  two  teeth  in  one  ar- 
cade, and  a  vacant  tooth  cavity  or  a  decayed  tooth,  in  the 


186 


ANIMAL   DKXTISTRY. 


opposing  one.  In  the  aggravated  forms  there  will  also  be 
a  considerable  excavation  of  the  jaw  in  the  vacant  cavity. 
Owing  to  the  freciucncy  of  decay  in  the  fourth  superior  molar 
the  condition  appears  chiefly  in  the  region  of  the  fourth  in- 
ferior molar. 

Treatment — Trimming  to  the  level  of  the  arcade  with 
the  lever  cutter  in  young  animals  and  extraction  in  the  aged 
patient.  In  horses  more  than  fifteen  years  old  the  implan- 
tation is  so  unstable  that  the  cutting  process  may  loosen  the 
tooth. 


Fig.  132. 
Typical  Case  of  Elongation  of  the  4th   Inferior   Molar    (Ostertag). 

OPERATION  OF  CUTTING  ELONGATIONS. 

Restraint — Standing  position  with  the  dental  halter  and 
without  the  use  of  the  speculum.  The  speculum  will  pre- 
vent placing  the  cutter  evenly  over  the  crown  of  the  tooth. 

Equipment — Dental  halter,  open  molar  cutter,  floats  and 
file. 

Modus  Operandi — For  the  left  side  guide  the  head  of  the 
cutter  to  the  tooth  with  the  left  hand,  as  the  other  hand 
supports    them    by    the    handles.     Place    the    left    handle 


ANIMAL  DENTISTRY. 


187 


of  the  cutter  against  the  chest  and  open  it  with  the  right 
hand,  then  adjust  the  jaws  over  the  base  of  the  elongation. 
Retract  the  left  hand  and  cut  off  the  tooth  with  both  hands. 
In  the  superior  arcades  the  great  volume  of  the  elongation 
may  necessitate  the  application  of  considerable  force.    Care 


Fig.  132a.     (Also  Fig.  92.) 
The  Open  Molar  Lever  Cutter. 

must  be  taken  in  aged  horses,  and  in  the  case  of  the  molars 
at  the  extremities  of  the  arcades,  that  the  tooth  is  not  loos- 
ened by  a  sudden  movement  of  the  patient's  head.  After 
cutting  the  elongation  the  arcade  is  leveled  with  the  floats 


Fig.  132b.     (Also  Fig.  98a.) 
Handles  for  Figs.  92,  92.\,  94,  94a,  95,  97  and  98. 

and  file.  Small  pointed  projections  on  the  inferior  arcades 
may  be  cut  with  the  closed  molar  trimmers  when  they  are 
too  narrow  for  the  large  opening  of  the  lever  cutter. 

ENAMEL  POINTS. 

Synonyms — Sharp    teeth.      Lateral    enamel    projections. 
Enamel  points  of  herbivora. 

Definition — Sharp  points  of  enamel  at  the  table  extrem- 


188 


ANIMAL  DENTISTRY. 


ity  of  the  longitudinal  ri(lL;os  of  the  molars,  occurring  along 
the  buccal  border  of  the  superior  arcades  and  the  lingual 
border   of  the   inferior. 

Etiology — Knaniel  points  are  not  pathological.  They 
are  a  normal  part  of  the  dental  mechanism,  serving  the  pur- 
pose of  a  rake  to  maintain  fibrous  forage  between  the  teeth. 
Being  normal  structures  their  causes  are  strictly  of  an  in- 
tended, predisposing  character,   namely: 

(1)  The  relative  narrowness  of  the  inferior  molars. 

(2)  The  relative  narrowness  of  the  lower  jaw. 

(3)  The  ginglymoid  character  of  the  temporo-maxil- 

lary  articulation,  limiting  the  lateral  motion  of 
the  jaw. 

(4)  The  longitudinal  ridges,  the  enamel  of  which  ren- 

ders possible  the  formation  of  points. 

(5)  The  herbivorous    characteristic    of   which    three 

substances  of  unequal  densities  are  in  wear. 

(6)  The  normal  wear  of  the  teeth. 

Symptoms — Under  strictly  natural  conditions  they  are 
not  harmful,  but  from  the  artificial  influences  to  which  the 
horse  is  subjected  they  frequently  wound  the  buccal  sur- 
faces. The  widely  accepted  impression  that  they  limit  mas- 
tication by  obstructing  the  free  lateral  swing  of  the  jaw  is  not 
founded  upon  facts.  Their  sole  harmful  effect  is  the  wound- 
ing of  the  mucous  membrane.  The  wounds  are  usually  lo- 
cated on  the  cheek  opposite  the  first  and  second,  and  fifth 
superior  molars.  The  former  are  caused  by  the  friction 
of  the  bit  and  bridle  and  the  latter  by  the  forcible  movements 
of  the  masseter  muscle.  The  lesions  vary  from  slight  ero- 
sions of  the  mucous  membrane  to  large  ulcer-like  patches 
one  inch  in  diameter.  Other  parts  of  the  cheek  and  the 
tongue  are  seldom  wounded.  They  attain  the  greatest  size 
between  the  ages  of  5  and  8  years. 

Wounds  of  the  cheeks  which  are  being  perpetually  ag- 


.       ANIMAL  DENTISTRY.  189 

gravated  by  enamel  points  limit  mastication  and  favor  gas- 
tric indigestion.  In  drivers,  runners  and  saddle  horses  they 
are  the  greatest  sources  of  annoyance.  The  expert  reinsman 
will  promptly  recognize  their  presence  by  the  horse's  be- 
havior in  harness.  Lugging,  side-reining,  ptyalism,  tender- 
ness about  the  seat  of  bit,  manifestations  of  pain  from  the 
bridle  are  symptoms  of  these  lesions. 

Treatment — The  treatment  consists  of  filing  with  the 
floats  and  file.  Trimming  with  the  closed  molar  trimmers 
(Fig.  91)  preceding  the  filing  cannot  be  defended  by  any 
logical  argument.  If  this  instrument  could  be  accurately 
adjusted  to  the  very  tips  of  the  points,  as  they  are  intended, 
they  would  materially  lessen  the  labor  of  the  operation,  but 
as  only  the  very  skillful  operator  can  properly  accomplish 
this  feat,  the  use  of  the  trimmers  should  be  dispensed  with 
in  the  interest  of  judicious  and  scientific  dentistry.  A  few 
carefully  directed  strokes  of  the  float  equipped  with  the  rasp 
blade  will  rapidly  blunt  the  sharp  projections  to  the  desired 
point.  Rounding  the  borders  of  the  molars  is  harmful.  The 
aim  in  dressing  the  teeth  of  a  horse  should  be  to  simply  blunt 
the  enamel  points  along  the  course  of  the  arcades  and  to 
"round  up"  the  first  superior  and  first  inferior  molars  as 
smooth  as  an  ivory  ball.  The  wounds  from  the  bridle  are 
thus  prevented  and  there  will  be  no  interference  with  mas- 
tication from  the  too  liberal  use  of  instruments  along  the 
whole  arcade.  The  closed  incisor  trimmers  are  indispensable 
to  trim  the  projection  at  the  extremities  of  the  arcades,  and 
on  the  first  inferior  molar  the  angular  trimmer  may  be 
used.     (Fig.  98.) 

OPERATION    OF  TRIMMING   AND   FLOATING  THE  MOLARS 

Equipment — Straight  float,  angular  float,  closed  molar 
trimmers,  twelve-inch  file,  a  pail  of  water,  and  the  dental 
halter. 


190  ANIMAL  DENTISTRY. 

Restraint — Tlie  horse  is  secured  in  the  standing  position, 
backed  into  a  single  stall  and  fastened  to  the  pillar  with  the 
dental  halter.  The  halter  ropes  are  fastened  to  the  pillars 
low  enough  to  hold  the  head  at  the  proper  height.  When 
the  construction  of  the  pillars  prevents  tying  the  ropes  low 
enough,  an  additional  rope  is  fastened  from  the  halter  at  the 
lower  extremity  of  the  iron  band  and  passed  between  the 
forelegs  around  the  withers,  and  back  again  between  the 
legs  to  the  halter,  for  the  purpose  of  preventing  the  head 
from  being  held  too  high.  This  method  is  also  serviceable 
in  securing  horses  in  a  loose  box  or  paddock  where  stalls 
are  wanting.     (See  Fig.  105.) 

The  mouth  speculum  must  be  dispensed  with,  as  it  posi- 
tively interferes  with  the  free  use  of  the  instruments  and 
provokes  resistance,  which  is  otherwise  avoided.  The  twitch 
also  is  contra-indicated,  even  on  the  vicious  animal. 

The  aiin  in  securing  the  horse,  as  in  performing  the  oper- 
ation, is  to  avoid  the  use  of  any  force  that  will  be  resented. 

Examination  of  the  Mouth — First,  the  incisors  are  in- 
spected to  determine  the  age  and  the  presence  of  any  harm- 
ful disorders  or  irregularities.  Then  the  palmar  surface  of 
the  thumbs  is  passed  along  the  interdental  space  of  the  lower 
jaw  to  locate  possible  bit  lesions,  and  without  withdrawing 
them  they  are  turned  upward  against  the  interdental  space 
of  the  upper  jaw  to  palpate  for  wolf  teeth.  Third,  the  mo- 
lars are  palpated  by  passing  the  hand  backwards  between 
the  tongue  and  molar  arcades.   (See  diagnosis.) 

Modus  Operandi — The  canines  may  first  be  blunted  with 
the  twelve-inch  file,  to  prevent  wounding  the  hands,  but  the 
blunting  process  must  be  limited  to  the  very  tips  of  the 
crowns,  owing  to  the  fact  that  a  short  blunt  canine  gives  the 
appearance  of  age,  and  thus  leaves  an  opportunity  for  just 
criticism. 

The  second  step  of  the  operation  consists  of  trimming  the 


ANIMAL  DENTISTRY.  191 

ends  of  the  arcades,  with  the  closed  molar  trimmers,  but 
only  when  the  projections  are  long  enough  to  warrant  their 
use.  The  first  superior  molar  and  the  sixth  inferior  alone 
require  this  treatment,   in  the  normal  mouth. 

The  remainder  of  the  operation — the  floating  and  filing — 
is  performed  as  follows : 

ist.  Float  the  posterior  two-thirds  of  the  right  superior 
arcade,  with  the  straight  float,  the  anterior  one-third  with 
the  angular  float,  and  then  blunt  the  anterior  end  of  the  first 
molar  with  the  twelve-inch  file. 

2nd.  Observe  the  same  routine  on  the  left  superior  ar- 
cade. 


ar 


Fig. 


Fig.  89a. 
Straight  and  Angular  Floats,  with  Lines  showing  the  Proper  Angle  of 

Each. 

3rd.  Float  the  entire  left  inferior  arcade  with  the 
straight  float,  and  bevel  smoothly  the  anterior  end  of  the 
first  molar  with  the  twelve-inch  file. 

4th.  Observe  the  same  routine  on  the  right  inferior  ar- 
cade. 

5th.  Extract  wolf  teeth,  if  any  exist,  and  complete  the 
operation  by  blunting  any  sharp  projection,  on  the  superior 
molar,  that  may  exist  behind  them,  and  which  could  not  have 
been  reached  prior  to  their  extraction. 

It  will  be  observed  that  in  the  above  routine  the  arcades 
beginning  with  the  right  superior,  are  dressed  consecutively. 
The  work  on  each  one  is  completed  before  passing  to  the 
next,  until  all  four  have  been  perfectly  attended  to.     The 


192 


ANIMAL  DENTISTRY. 


only  objection  to  this  order  of  nianij)uiations  is  the  loss  of 
time  consumed  in  chantjini;-  instruments.  When  speed  is  a 
consideration,  all  the  work  re(|uired  of  each  instrument  is 
completed  before  the  instrument  is  laid  aside,  as  follows: 

I  St.  Float  the  posterior  two-thirds  of  the  superior  ar- 
cades, and  all  of  both  infe'rior  arcades,  with  the  straig-ht 
float. 

2nd.  Float  the  anterior  one-third  of  the  superior  ar- 
cades, with  the  ang-ular  f^oat. 

3rd.  Blunt  and  bevel  the  ends  of  the  arcades  with  the 
twelve-inch  file. 

Whatever  is  adopted,  it  will  be  found  advantageous  to 


Fig.  90. 

form  the  liabit  of  following  the  routine  in  either  plan,  in 
order  to  avoid  omissions  and  unnecessary  examinations  of 
the  mouth  to  determine  the  amount  of  filing  that  has  been 
done.  It  is  an  error  to  use  the  floats  promiscuously  and  to 
repeatedly  palpate  to  note  the  results.  Such  methods  pro- 
voke resistance,  which  is  avoided  in  more  systematic  work. 

METHOD  OF  USING  THE  FLOATS  AND  FILES  IN  THE  FORE- 
GOING OPERATION. 

It  is  undeniable  that  one  operator  can  float  the  teeth 
of  horses,  and  in  fact,  use  any  of  the  dental  instruments 
without  provoking  the  least  resistance,  while  another  will 
have  more  or  less  trouble  with  every  animal  approached. 
So  marked  is  the  difference  in  this  connection  that  bystand- 


ANIMAL    DENTISTRY. 


193 


ers  frequently  gain  the  impression  that  some  operators  exert 
a  mysterious  influence  over  their  patients.  The  secret  Hes 
solely  in  avoiding  the  use  of  force.  A  horse  will  resent 
forcible  opening  of  the  jaw,  forcible  insertion  of  the  hand 
backwards  into  the  molar  region,  forcible  restraint,  and 
injury  to  the  soft  structures  inflicted  by  improperly  directed 
instruments.  In  avoiding  these  manipulations  the  secret  is 
found.     Forcible  opening  of  the   mouth   is   unnecessary  in 


Fig.  133. 
Position  of  Hands  to  Float  the  Right  Superior  Molar  Arcade. 

using  the  float.  As  only  the  edges  of  the  arcades  are  floated 
the  instrument  may  be  passed  unobstructed  to  their  very 
end  without  opening  the  mouth  more  than  half  an  inch.  In 
the  lower  arcades  the  hand  must  be  passed  into  the  inter- 
dental space  to  guide  the  shaft  of  the  float,  and,  as  a  result, 
the  mouth  is  opened  slightly  more  than  in  floating  the 
superior  ones,  but  to  prevent  resentment,  the  hand  in  the 
interdental  space  must  not  be  used  to  force  the  mouth 
open  when  the  animal  attempts  to  close  upon  it.     Its  pres- 


194 


ANIMAL   IJICNTISTRY. 


ence  there  is  simply  to  guide  tlie  lloat  and  not  to  open  tlie 
mouth.  Injury  to  the  hand  is  prevented  by  keeping  it  where 
it  cannot  be  squeezed  when  the  mouth  is  closed.  Resistance 
is  usually  provoked  in  this  manner  by  forcibly  attempting  to 
prevent  closure  of  the  mouth  in  fear  of  being  bitten.  The 
operator  must  learn  to  place  the  hand  only  where  it  cannot 
be  bitten  or  squeezed,  and  the  horse  must  be  permitted  to 
use  its  jaw  ad  libitum.     "J'he  dental  operation  must  not  be  a 


Fig.  134. 
Position  of  Hands  to  Float  the  Left  Superior  Molar  Arcade. 

fight  for  superiority  in  strength  between  the  dentist's  hand 
and  the  patient's  jaw.  The  following  position  of  the  hands 
to  guide  the  instruments  will  serve  the  purpose. 

For  the  right  superior  arcade  place  the  tips  of  the  fingers 
of  the  left  hand  palm  upwards,  into  the  interdental  space, 
just  in  front  of  the  commissure,  or,  in  other  words,  in  front 
of  the  first  superior  molar.  Work  the  float  with  the  right 
hand  and  guide  its  shaft  with  the  palmar  surface  of  the 
fingers  of  the  left.     In  this  position  the  finger  tips  are  not 


ANIMAL  DENTISTRY. 


195 


passed  beyond  the  outer  border  of  the  jaw  (upper  branch 
of  the  premaxilla)  but  are  fortified  gently  upon  it.  The 
float  head  is  kept  flat  against  the  outer  edge  of  the  arcade 
and  not  upon  the  table  surface.     (See  Fig.  133.) 

For  the  left  superior  arcade  pass  the  left  hand,  palm  up- 
ward, through  the  interdental  space,  from  right  to  left,  until 
the  tips  of  the  fingers  protrude  slightly  from  the  left  commis- 
sure, and  let  the  thumb  rest  easily  on  the  palate  in  the  re- 


FiG.  135. 
Position  of  the  Hands  to  Float  the  Left  Inferior  Molar  Arcade. 

gion  of  the  first  superior  molar.  Work  the  float  with  the 
right  hand  and  guide  the  shaft  with  the  palmar  surface  of 
the  fingers  of  the  left.     (See  Fig.  134.) 

For  the  left  inferior  arcade  pass  the  left  hand,  palm  down- 
ward, through  the  interdental  space,  from  right  to  left,  under 
the  tongue,  and  when  the  left  border  of  the  tongue  is  reached 
with  the  finger  tips,  direct  the  hand  upward  between  the 
tongue  and  left  arcades  (the  dorsal  surface  to  the  tongue 
and  palmar  surface  to  the  arcades),  and  let  the  thumb  pro- 


196 


ANIMAL  l)i:X'riSTRV 


triulc  throui^h  ihc  left  coinniissurc.  In  this  position  the 
anterior  end  of  the  arcacle  lies  l)et\vccii  the  thunih  and  first 
finger,  and  the  wrist  is  ke])t  Hat  on  the  interdental  space  of 
the  lower  jaw.  to  keej)  the  tongne  from  slipi^ng-  beneath  it. 
The  float  is  worked  with  the  right  hand,  and  the  shaft  is 
g-uided  by  tlie  palmar  surface  of  the  base  of  the  thumb.  The 
float  head  is  kept  flat  against  the  internal  border  of  the 
arcade,  and  not  on  the  tables.     (See  Fig.  135.) 


Fig.  136. 
Position  of  the  Hands  to  Float  the  Right  Inferior  Alolar  Arcade. 

For  the  right  inferior  arcade  place  the  right  hand  in  the 
same  relative  position  as  the  left  was  placed  for  the  oppo- 
site inferior  arcade,  and  work  the  float  with  the  left  hand. 
Although  the  left  hand  is  the  awkward  one,  it  is  advisable 
to  train  it  to  accomplish  this  feat,  as  it  is  the  only  position 
that  will  give  universal  satisfaction.  Another  method  con- 
sists of  placing  the  left  hand  upright  into  the  interdental 
space  and  guiding  the  shaft  between  the  second  and  third, 
or  third  and  fourth  fingers.     Still  another  method  consists 


ANIMAL  DENTISTRY. 


197 


of  passing  the  left  hand  into  the  interdental  space,  through 
the  right  commissure,  grasping  the  free  end  of  the  tongue 
firmly  with  the  fingers  and  then  passing  it  gently  out  of  the 
opposite  commissure.  In  this  position  the  float  is  worked 
with  the  right  hand,  and  the  shaft  is  guided  by  the  wrist, 
which  is  slightly  arched  upward  into  the  roof  of  the  mouth. 
The  right  inferior  arcade  is  more  difficult  to  float  than  the 
others  and  as  a  result  is  usually  found  neglected  posteriorly. 
(See  Fig.  136.) 


Wt^^'i'^'W-  ^^v 

%^. 

0  ^ 

1r 

^^m 

h 

,„jbI^ 

'^ 

^HB 

i. 

{^ 

Fig.  137. 
Position  of  the  Hands  and  File  to  Blunt  the  Right  First  Superior  Molar. 

To  blunt  the  right  first  superior  molar  place  the  left  hand 
into  the  right  commissure  between  the  cheek  and  the  molar 
arcades,  then  pass  the  twelve-inch  file  (in  the  right  hand) 
through  the  interdental  space  from  the  opposite  commissure 
to  its  finger  tips.  Work  the  file  with  the  right  hand  and 
guide  it  around  the  end  and  side  of  the  arcade  with  the  finger 
tips  of  the  left.  Change  positions  to  round  the  arcade  an- 
teriuriy  and  internally  as  follows:  Place  the  left  hand  to- 
ward the  nasal  roof  and  the  thumb  into  the  commissure  to 


198 


ANIMAL   DENTISTRY. 


retracu  and  elevate  it,  then  work  the  file  with  the  right  hand. 
(See  Figs.  I4i-i37-) 

To  blunt  the  left  first  superior  molar  place  the  right  hand 
in  the  left  commissure,  between  the  cheek  and  teeth,  then 
pass  the  twelve-inch  file  through  the  interdental  space  from 
the  opposite  side  to  the  finger  tips  of  the  right  hand.  Work 
the  file  with  the  left  hand  and  guide  it  with  the  finger  tips  of 
the  right.     Change  the  position  to  blunt  the  anterior  end  of 


Fig.  138. 
Second   Position   of  the  Hands  and  File  to   Blunt  the  Left  First    Superior 

Molar. 

the  tooth,  as  follows :  Place  the  palm  of  the  left  hand  over 
the  nose  and  w^ith  the  thumb  retract  and  elevate  the  com- 
missure of  the  mouth,  then  work  the  file  with  the  right  hand 
.^s  in  filing  the  opposite  side.     (See  Fig.  138.) 

To  bevel  the  right  first  inferior  molar  place  the  palm  of 
the  left  hand  on  the  inferior  border  of  the  lower  ]a.w,  and  re- 
tract and  depress  the  commissure  with  the  thumb,  then  work 
the  file  v^ith  the  right  hand.     (Fig.  139.)    Change  the  position 


ANIMAL   DENTISTRY. 


199 


as  follows :  Pass  the  file  through  the  interdental  space  from 
left  to  right,  and  hold  it  upon  the  tooth  with  the  thumb  of 
the  left  hand,  then  work  the  file  by  short  movements  of 
both  hands. 

To  bevel  the  left  first  inferior  molar  open  the  mouth 
gently  by  grasping  the  tongue  and  turning  it  perpendicularly 
in  the  interdental  space;  then  work  the  file  over  the  molar 
with  the  right   hand.     The  beveling  process   mav  be   ore- 


FiG.  139. 

First  Position   of  the   Hands  and   File  to   Bevel   and   Blunt  the   JKight   First 

Inferior  Molar. 

ceded,  to  advantage,  by  first  trimming  the  anterior  angle 
of  the  crowns  with  the  angular  cutter.     (See  Fig.  140  ) 

The  above  is  simply  "a"  method  by  which  the  sharp 
points  on  the  molars  may  be  blunted  with  but  little  labor,  and 
without  provoking  resentment  from  the  horse.  Other  meth- 
ods may  serve  the  same  purpose,  providing  they  can  be 
carried  out  without  the  use  of  force. 

Occasionally  a  horse  that  has  been  roughly  handled  or 


200 


ANIMAL   DENTISTRY. 


one  that  has  never  become  accustomed  to  i)eing  handled 
about  the  head,  will  resent  the  attempt  to  open  the 
mouth  when  first  approached.  Such  animals  can  never  be 
conquered  by  force  or  rough  treatment,  sufficiently  to  enable 
the  operator  to  properly  carry  out  the  procedure,  but  by 
the  use  of  kindness  and  gentle  manipulations  to  first  gain 
the  patient's  confidence,  few  dental  operations  need  be 
abandoned  on  account  of  resentment.     It  will  be  found  that 


Fig.  140. 
Position  of  trie  Hand  and  Fife  to  Bevet  and  Bfunt  tfie  Left  First  Inferior 

Molar. 

the  most  resistance  is  offered  by  such  horses  while  the  float 
is  being  adjusted  to  the  teeth  or  while  the  hand  is  being 
placed  in  position  to  receive  the  float,  and  that  the  resistance 
immediately  ceases  as  soon  as  the  filing  begins.  The  re- 
markable fact  that  a  horse  will  stand  "at  attention"  while 
the  rasping  proceeds  suggests  itself  as  a  method  of  taking 
advantage  of  a  resisting  horse.  Instead  of  first  placing  the 
hand  into  the  interdental  space,    the    float    may    first    be 


ANIMAL  DENTISTRY. 


201 


promptly  passed  into  the  mouth,  and  as  the  horse  becomes 
attracted  by  the  vmusual  sound  and  sensation  produced  by 
the  filing  no  further  resistance  may  be  offered  and  the  hand 
may  then  be  placed  unresented  into  the  interdental  space  to 
guide  the  float. 

Enamel  points  will  recur  in  about  three  months,  but  not 
to  a  sufficient  degree  to  produce  injury  until  the  twelfth  to 
the  eighteenth  month  after  the  operation.    At  the  age  of  five 


Fig.  141. 

Position  of  the   Hands  and   File  to   Complete   the   Blunting   Process  on   the 

Superior   Molars,   Externally. 

to  eight  years  their  recurrence  is  more  rapid  than  in  aged 
animals. 

Modifications — When  one  of  the  arcades  contains  a  de- 
cayed or  elongated  molar  the  normal  arcades  are  floated 
and  filed  before  any  attention  is  given  to  the  abnormal  one. 
The  painful  part  of  the  o])eration  is  performed  last  to  avoid 
the  resistance  that  nu"ght  be  provoked  thereby,  and  when  a 
tooth   is   extracted,   to  avoid   working  in   a   bloody   mouth. 


202  ANIMAL    DENTISTRY. 

Ill  very  vicious  animals  the  recuinl)ent  i)osition  may  be  neces- 
sary to  properly  trim  the  molar  teeth,  l)ut  such  animals  are 
rarely  encountered.  In  our  experience  with  upwards  of  fifty 
thousand  horses  only  two  such  cases  have  been  met — one 
was  a  trotting  bred  stallion  and  the  other  a  hackney  gelding. 
Both  of  these  animals  would  resent  any  attempt  to  place  a 
float  into  the  mouth  by  striking  viciously  with  the  fore  feet. 
In  such  cases  the  veterinarian  is  warranted  in  resorting  to  ar- 
appropriate  means  of  restraint,  in  the  recumbent  position. 

FLOATING  THE  TEETH  OF  THE  OX. 

The  ox  carries  the  head  low,  has  an  unyielding  tongue 
and  a  strong  jaw  and  is  so  unaccustomed  to  being  handled 
about  the  mouth  that  it  makes  a  rather  unwelcome  subject 
for  dental  operations.  These  obstacles  are  met  by  securing 
the  head  and  neck  to  the  post  of  the  stall,  in  an  upward 
inclination,  and  by  keeping  the  mouth  open  with  a  strong 
speculum  consisting  of  an  oblong  loop  of  iron  placed  within 
the  interdental  space.  The  ordinary  horse  speculum  is  too 
frail  to  withstand  the  forcible  jaw^  of  an  ox. 

The  superior  arcades  are  floated  with  the  hand  in  the 
same  position  as  in  the  horse,  but  in  the  inferior  ones  it  is 
kept  in  the  interdental  space  and  not  between  the  tongue 
and  teeth.  The  float  is  directed  from  within  outward  to 
follow  the  direction  of  the  arcades. 

Enamel  points  are  less  harmful  in  the  ox  owing  to  the 
toughness  of  the  buccal  mucosa,  yet  buccal  wounds  from 
sharp  teeth  are  not  uncommon  in  animals  past  the  age  of 
three  years. 

WOLF  TEETH. 

Synonyms — Remnant  teeth.  Supernumerary  teeth.  Sup- 
plementary teeth.     Eye  teeth. 

Definition — The  wolf  teeth  may  be  defined  as  retrogres- 
sive teeth   representing  the    premolars    of    the    prehistoric 


ANIMAL  DENTISTRY. 


203 


horse.  They  are  not  the  result  of  accidental  dental  develop- 
ment but  a  constant  normal  part  of  the  equine  denture  un- 
dergoing degeneration  under  the  influence  of  selection,  as 
the  "wisdom  teeth"  of  man  are  disappearing  under  the  in- 
lluence  of  civilization.  The  use  of  the  bit  through  innumer- 
abe  generations  appears  to  have  rid  the  interdental  space 
of  the  premolars. 

Wolf  teeth  are  constant  in  foetal  life  in  both  the  inferior 
and  superior  dentures,  and  many  of  them  never  develop  to 
the  point  of  eruption,  but  instead  degenerate,  and  become 
incorporated  with  the  maxilla.  Those  which  finally  erupt 
vary  from  small  homogeneous  masses  of  soft  dentine  to  well 


Fig.  142. 
Wolf-Teeth. 

developed  teeth  possessing  all  the  distinguishing  character- 
istics of  the  herbivorous  molar. 

Symptoms — Wolf  teeth  are  harmless  with  the  exception 
of  their  possible  interference  with  the  overcheck  bit  or  com- 
plicated coach-horse  rigging,  such  as  bridoons.  They  have 
no  effect  upon  the  eyes,  and  are  diagnosed  solely  by  palpa- 
tion. Their  position  is  the  interdental  space  of  the  upper 
jaw,  more  or  less  closely  related  to  the  first  molar.  In  some 
instances  they  are  located  on  the  inner  aspect  of  the  molar 
and  occasionally  on  the  lower  jaw. 

Treatment — The  wolf  tooth  should  he  extracted,  as  it 
serves  no  useful  purpose  and  may  at  some  time  interfere 


2U4 


ANIMAL   DICX'l'IS'l'KV 


with  the  hitlinj;"  rii;\uin_Lj;-  of  a  (h-i\in_!^-  horse.  In  the  treat- 
ment of  eye  affection  their  extraction  is  particularly  advis- 
able, owing  to  the  popular  prejudice  against  them. 

They  are  difficult  to  extract  without  fracture  because 
their  location  prevents  direct  outward  traction  and  because 
of  the  impossibility  of  perfectly  immobilizing  the  head  and 
especially  the  lower  jaw.  Their  removal  is  accomplished  by 
first  disturbing  their  implantation  with  the  wolf  tooth  sep- 
arator (Fig.  93)  prior  to  the  application  of  outward  traction 
with  the  forceps,  or  with  the  seDarator  alone. 


Fig.  14.?. 
Supcrnnnierary    Incisors    of   a    6- Year-Old    Gelding. 

SUPERNUMERARY  TEETH. 

Definition — Teeth  existing  in  excess  of  the  normal  num- 
ber in  any  of  the  arcades,  are  designated  as  supernumerary. 
They  must  be  differentiated  from  wolf  teeth,  which  are  nor- 
mal structure  and  from  persisting  temporary  teeth,  due  to 
displacement  of  the  permanent  tooth  germ. 

Etiology — The  supernumerary  teeth  result  from  the  pro- 
jection of  more  than  one  stalk  from  the  common  enamel 
germ.  This  occurrence  is  frequent  if  not  universal,  but  un- 
der normal  development,  all  the  stalks  degenerate  as  a  chief 
one  predominates.  Wlienever  two  or  more  keep  pace  with 
one  another  until  tooth  development  is  well  advanced,  the 


ANIMAL  DENTISTRY. 


205 


result  is  the  formation  and  growth  of  more  than  one  tooth 
at  a  given  point.  Some  such  teeth  may  never  erupt,  but 
remain  imbedded  in  the  jaw  along  the  arcade. 

An  additional  seventh  molar  frequently  occurs  behind  the 
sixth   in  either  arcade.      This   incident   is   the   result   of  the 


Fig.  144. 
Supernumerary    Incisors    of   a   9-Year-Old    Horse. 

backward  extension  of  the  common  enamel  germ  from  pre- 
cocity of  the  sixth  molar. 

Symptoms — The  abnormality  is  observed  chiefly  in  the 
incisor  arcades  which  may  contain  an  entire  double  row  of 
teeth.     In  most  instances  one  or  two  additional  incisors  are 


Fig.  145. 
Supernumerary   Molars. 

observed  projecting  in  an  irregular  fashion  to  the  table  level 
of  the  arcade.  The  lateral  incisors  are  most  frequently  the 
seat  of  the  abnormality. 

In  the  molar  arcades  they  may  remain  hidden  through 


206  ANIMAL  DKNTISTRV. 

iifc,  or  remain  unobserved  until  tlieir  existence  is  revealed 
in  the  treatment  of  diseased  conditions — extractini;",  trephin- 
inj;",  etc. 

Treatment — As  long  as  the  supernumerary  tooth  pro- 
duces no  apparent  harm  no  treatment  is  advisable.  In  the 
incisor  arcades  their  extraction  gives  even  a  worse  appear- 
ance to  the  arcade  than  if  they  had  been  left  undisturbed. 
When  encountered  within  the  sinuses  in  the  course  of  den- 
tal operations  they  are  removed  or  left  undisturbed,  ac- 
cording to  whether  they  are  involved  in  the  morbid  process. 

ELONGATIONS  OF  THE  INCISORS. 

As  decay  or  loss  of  incisor  teeth  is  a  rare  condition  ac- 
quired elongations  of  the  incisors  by  growth  into  vacant 
cavities  are  also  rare.  The  gradual  lengthening  of  the  whole 
superior  incisive  arcade  as  an  animal  becomes  older  is  a 
natural  condition  resulting  from  a  gradual  receding  of  the 
alveolar  border,  and  the  constant  increase  in  the  inclination. 

The  common  impression,  especially  among  laymen,  that 
the  elongation  of  the  incisors  prevents  contact  of  the  molar 
denture  is  erroneous.  The  only  detriment  is  the  evidence 
they  furnish  of  the  real  age  of  the  animal,  on  which  account 
alone  their  shortening  is  advisable.  Shortening  the  superior 
incisors  of  the  old  horse  is  always  harmful  in  proportion  to 
the  amount  removed.  Prehension  of  attached  food  is  im- 
paired. 

SHORTENING  THE  INCISOR  TEETH. 

The  incisor  teeth  of  the  horse  are  reduced  in  length  for 
the  purpose  of  disguising  the  evidence  they  furnish  as  to 
the  age  of  the  subject.  The  popular  impression  that  they 
prevent  contact  of  the  molars  is  as  positively  ridiculous  is  it 
is  physically  impossible.  The  incisors  can  only  wear  as  fast 
as  the  molars  will  permit  them,  and  vice  versa.  In  rare 
instances  the  veterinarian  is  required  to  reduce  their  length, 


ANIMAL   DENTISTRY. 


207 


to  hide  the  crowns  beneath  the  lips,  when  the  latter  no  longer 
cover  them  completely,  in  which  case  only  the  operation 
is  excusable. 

The  operation  is  performed  only  upon  the  superior  ar- 
cade, as  the  inferior  one  is  seldom  inspected  for  its  senile 
changes. 

Modus  Operandi — First,  cut  off  the  internal  table  angle 
of  each  corner  tooth  and  file  them  to  the  length  decided  upon, 
and  then  use  the  length  as  a  guide  for  reducing  the  remain- 
der of  the  arcade.  Second,  file  a  deep  groove,  through  the 
enamel  across  the  laterals  and  centrals  connecting  the  new 
table  level  of  the  corners.     Third,  cut  off  the  laterals  with 


H^uSSW^"" 


Fig.  145a.  Fig.  145b. 

Lip  Retractor  and  Mouth  Gag,  useful  in  shortening  incisor  teeth. 

the  nippers  and  file  them  to  the  level  of  the  corners.  Fourth, 
cut  off  the  centrals  and  file  them  to  the  level  of  the  laterals. 
Fifth,  bevel  the  tables  backwards  by  patient  filing.  Sixth, 
remove  the  crusta  petrosa  and  tartar  and  polish  with  emery 
paper. 

In  cutting  the  incisors  great  care  is  necessary  to  prevent 
chipping  of  the  enamel,  which  accident  will  leave  an  un- 
sightly defect  in  the  arcade.  The  accident  is  prevented  by 
cutting  the  transverse  groove  completely  through  the 
enamel  and  by  not  grasping  too  much  substance  with  the 
nippers.  It  is  preferable  to  cut  an  incisor  tooth  by  small 
sections,  rather  than  by  grasping  the  entire  crown. 


208  ANIMAL   DKNTISTRV. 

EROSION  OF  THE  ENAMEL. 

Definition — A  disease  of  tlie  anterior  face  of  the  superior 
incisor  teeth,  characterized  by  a  gradual  upward  denuding  ol 
the  external   enamel   covering. 

Etiology — The  cause  depends  solely  upon  a  faulty  con- 
struction of  the  teeth,  both  anatomically  and  morphologi- 
cally. The  disease  occurs  in  animals  having  an  observable 
softness  of  all  the  teeth.  The  dentine  is  devoid  of  its  char- 
acteristic hardness  and  the  crusta  petrosa  is  deficient  in  qual- 
ity as  well  as  quantity.  Defective  cementing  of  the  enamel 
to  a  soft  underlying  dentine  favors  the  gradual  breaking 
and  wearing  away  of  the  former.  Iron  feed  boxes,  cribbing 
and  the  habit  of  gnawing  hard  objects  hurry  the  denuding 
process,  but  are  never  solely  responsible. 

Treatment — ^Polishing  with  emery  paper  to  give  a  better 
appearance  is  the  only  possible  help. 

TARTAR. 

Definition — An  accumulation  of  calcareous  matter  along 
the  gingival  margin  of  the  teeth. 

Etiology — Tartar  simulates  calculi  in  other  parts  of  the 
body.  It  is  the  result  of  the  chemical  action  of  saliva  and 
mucus  on  the  calcium  salts  of  the  food.   It  is  composed  of 

Phosphates   80. 

Mucus 1 1.5 

Ptyaline i. 

Animal  matter 7.5 

Symptoms — Tartar  occurs  as  a  yellow  incrustation  along 
the  gums.  In  animals  it  is  found  mostly  on  the  canines  and 
incisors;  on  the  canines  it  frequently  accumulates  in  large 
quantities  and  gives  the  crown  the  appearance  of  a  mon- 
strosity (odontoma).  It  is  differentiated  from  the  latter  by 
being  readily  removed,  and  from  the  normal  crusta  petrosa 


ANIMAL  DENTISTRY.  209 

by  Its  lighter  color  and  by  not  adhering  firmiy  to  the  crown. 
Treatment — Tartar  is  removed  with  a  curette  or  file.    It 
produces  slight  irritation  of  the  gums. 

FRACTURE  OF  THE  TEETH. 

Fracture  of  the  teeth  occurs  to  the  incisors  from  falling 
or  stumbling  on  hard  pavements,  blows  or  kicks  from  other 
animals.  The  molars  seldom  sustain  such  injuries.  Frac- 
ture of  incisors  is  usually  complicated  with  considerable  con- 
tusion and  laceration  of  the  lip.  The  fractured  loose  sections 
must  be  removed  and  the  lip  treated  according  to  the  char- 
acter of  the  injury. 

SPLITTING  OF  THE  MOLARS. 

Synonym — Fissuring   of   the    molars. 

Definition — A  condition  peculiar  to  the  molars  of  her- 
bivorous animals  consisting  of  a  division  of  a  decayed  molar 
into  two  or  three  plate-like  segments. 

Etiology — Splitting  of  the  teeth  is  an  incident  of  the  ad- 
vanced stage  of  decay.  It  is  not  a  separate  entity  nor  an 
accident.  Pulpitis,  alveolar  periostitis  and  the  subsequent 
necrosis  following  these  inflammatory  conditions,  deprive 
the  tooth  of  its  nutrition  and  moisture,  and  the  resulting 
desiccation,  predisposed  by  the  "layer  arrangement"  of  the 
tooth,  favors  splitting  and  fissuring  as  a  termination  of  the 
disease  process.  In  the  long  process  of  decay  which  the 
molar  teeth  undergo,  splitting  is  the  incident  preceding  the 
final  ejection  of  the  tooth  from  its  cavity — self-extraction. 

Fissuring  limited  to  the  buccal  or  lingual  surface  of  the 
crown  in  the  absence  of  any  gross  lesion  is  also  of  common 
occurrence  to  the  back  molars  of  both  arcades.  This  condi- 
tion is  evidently  due  to  an  inadequate  union  between  the 
external  enamel  and  dentine  of  the  crown,  and  greatly  re- 


210  ANIMAL  DENTISTRY. 

scmhlcs  the  al)n()rnialil\-  of  tlic  incisors  known  as  "erosion" 
or  "denuding-."  It  is  a  liarniless  condition  in  itself,  but 
should  l)C  regarded  as  e\idcnce  of  a  poor  r|uality  of  teeth. 

Pathological  Anatomy — The  incident  occurs  most  fre- 
quently to  the  superior  molars,  but  is  seen  also  in  the  in- 
ferior ones.  The  splitting  may  be  limited  to  the  crown  or 
may  extend  through  the  entire  length  of  the  tooth.  In  the 
greatest  nund)er  of  cases  it  terminates  just  beyond  the  al- 
veolar margin  on  the  lingual  side  of  the  tooth,  dividing  it 
into  two  very  unequal  segments,  one  of  which  comprises  the 
principal  part  of  the  tooth,  and  the  other  a  thin  shell  consist- 
ing of  the  crusta  petrosa  and  external  enamel. 

In  other  instances  the  tooth  is  broken  into  three  seg- 
ments— two  lateral  shells  and  a  central  large  one,  which  in- 
cludes the  fang  and  roots. 

In  rare  cases  a  superior  molar  is  divided  into  two  equal 
portions  by  splitting  from  table  to  root  between  the  two 
layers  of  the  internal  enamel. 

The  condition  is  complicated  with  considerable  osteitis 
and  necrosis  from  lateral  pressure  against  the  alveolar  mar- 
gin, and  from  the  decomposition  of  impacted  food.  In  the 
old  case  the  opposing  tooth  will  be  found  elongated  and  the 
tongue  and  cheek  may  be  severely  wounded  from  friction 
of  the  protruding  segments. 

Treatment — Removal  of  the  tooth  and  leveling  of  the 
opposing  arcade.     (See  extraction.) 

FOREIGN  BODIES  IN  THE  MOUTH. 

Foreign  bodies  become  lodged  in  the  mouth  of  all  the  do- 
mestic animals.  In  the  horse  and  ox  pieces  of  corncob  and 
sticks  of  wood  become  wedged  between  the  superior  arcades, 
and  pins,  tacks  and  splinters  lodge  between  the  teeth.  In 
the  dog,  cat  and  pig,  pieces  of  bones  are  frequently  found. 


ANIMAL  DENTISTRY.  211 

In  one  case  a  tack  was  found  firmly  lodged  in  the  infundibu- 
lum  of  the  lateral  superior  incisor. 

Diagnosis — Attention  is  attracted  to  disturbed  mastica- 
tion, rejection  of  partially  masticated  food,  disinclination  to 
eat,  ptyalism  and  later  to  the  fetor  caused  by  pressure  necro- 
sis, and  the  decomposition  of  food. 

Treatment — Removal  of  the  object  followed  by  irriga- 
tions of  the  mouth  with  solution  of  borax,  alum  or  boric  acid. 

FRACTURE  OF  THE  INFERIOR  MAXILLA. 

Varieties: 

(i)   Simple  fracture  of  the  neck  of  one  ramus. 

(2)  Simple  fracture  of  the  neck  of  both  rami. 

(3)  Simple  fracture   of  one  ramus  along  the   molar 

arcade. 

(4)  Fracture  of  the  angle  without  dental  complica- 

tions,        .^■■^"■r^^' 

(5)  Comminuted  fracture  along  the  molar  arcade. 

(6)  Fracture  near  the  articulation. 

Etiology — Kicks  from  horses  sustained  as  the  victim  is 
walking  through  the  stable  aisle  is  the  most  common  cause 
of  fractures  of  the  inferior  maxilla.  Collisions  with  vehicles 
and  cars  and  other  forms  of  violence  seldom  fracture  this 
bone.  Solutions  in  the  continuity  of  the  ramus  from  bit 
gnathitis  is  an  occasional  cause  (see  page  214).  And  finally 
too  forcible  blows  on  a  misdirected  punch  while  repulsing 
teeth  occasionally  fractures  the  jaw.  In  the  dog  and  cat 
the  bite  sustained  during  a  fight  is  the  chief  cause  of  this 
injury. 

Symptoms — The  diagnosis  of  fractured  inferior  maxilla 
is  by  no  means  a  simple  matter  under  all  circumstances.  The 
subject  is  usually  presented  several  days  after  the  accident,  at 
which  time  the  tumefaction  will  require  differentiation  from 
other  diseased   condition   characterized   by   enlargement   of 


212 


ANIMAL  DENTISTRY. 


the  inferior  maxilla.  In  the  recent  case  the  diagnosis  is 
equally  difficult  owing  to  the  liability  of  the  fracture  remain- 
ing a  subperiosteal  one  until  displacement  occurs  from  move- 
ments of  the  jaw,  some  days  later,  at  which  time  the  condi- 
tion continues  to  be  masked  by  swelling. 

Deformity  at  the  angle,  crepitation  or  movement  of  the 
fractured  ends  felt  within  the  mouth  as  the  jaw  is  moved 
with  the  other  hand,  and  the  loosening  of  one  or  more  mo- 
lars, will  confirm  a  diagnosis,  but  in  the  absence  of  these 
plain  pathognomonic  symptoms  the  nature  of  the  injury  may 
remain   masked   until   an   abscess   forms   and   points   to  the 


Fig.  146. 
A  Well  Healed  Comminuted  Fracture  of  the  Inferior  IMaxilla,  with  Dental 

Complications. 

surface   and   thereby  admits   direct   palpation   of   the   bone 
Fracture    of  the  neck  of  one  or  both  rami  is  easily  recog- 
nized by  palpation. 

In  addition  to  the  above  phenomena  there  is  always  a 
serious  disturbance  to  mastication.  There  will  be  little  in- 
clination to  eat  during  the  first  days,  but  finally,  from  sheer 
starvation,  food  will  be  ingested  unmasticated,  in  which 
condition  it  will  be  found  in  the  feces.  The  subject  will 
lose  flesh  rapidly,  become  emaciated,  suffer  from  colics 
and  probably  die. 

Treatment — The  principal  treatment  consists  of  feeding 
crushed  food  and  liquid  food,  in  order  to  prevent  unnecessary 


ANIMAL  DENTISTRY.  213 

use  of  the  jaw.  Appliances  to  immobolize  the  fracture  are 
never  satisfactorily  retained,  and  prove  of  little  service. 
When  abscesses  form  their  contents  are  evacuated  and  the 
wound  searched  for  comminuted  segments.  The  loose  teeth 
must  be  extracted. 

In  fracture  of  both  rami  near  the  incisor  teeth,  in  small 
animals  amputation  can  be  successfully  performed. 

Prognosis — In  young  animals  even  the  severe  commi- 
nuted fractures  may  reunite  by  an  extensive  deposit  of  new 
bone,  and  the  patient  make  a  rather  tardy  recovery  with  con- 
siderable permanent  tumefaction  of  the  jaw.  In  old  animals 
the  bad  fracture  is  always  fatal.  Fractures  of  one  ramus 
near  the  neck  is  not  serious  and  will  reunite  with  but  little 
deformity  and  only  slight  interference  with  the  general 
health.  Fractures  without  dental  complication  are  less  seri- 
ous than  those  involving  the  molar  teeth. 

FRACTURES     OF    THE     PREMAXILLA     AND     SU- 
PERIOR MAXILLA. 

Although  the  premaxilla  is  an  exposed  bone,  its  fracture 
is  remarkably  rare.  The  superior  branch  is  occasionally 
fractured  from  a  kick,  and  the  body  from  a  fall  upon  the 
incisor  teeth.  The  superior  maxillary  is  frequently  frac- 
tured conjointly  with  the  other  facial  bones  as  a  result  of 
kicks  or  other  of  the  usual  forms  of  violence.  Owing  to 
the  fixed  articulations  of  these  bones  fractures  recover 
promptly  and  without  much  deformity.  Crushing  of  the 
maxillary  spine  leaves  a  somewhat  unsightly  blemish,  but 
otherwise  these  lesions  are  not  serious. 

DISLOCATION    OF    THE    TEMPORO-MAXILLARY 
ARTICULATION. 

Etiology — This  dislocation  is  possible  only  in  the  car- 
nivora.    In  the  herbivora  the  arrangement  of  the  condyle  and 


214  ANIMAL  DENTISTRY. 

coronoid  process  prevents  luxation.  In  the  dog  it  occurs 
wliile  masticating  bones,  or  in  yawning. 

Pathological  Anatomy — The  dislocation  is  a  forward 
one  in  all  instances  and  like  all  luxations  is  accompanied  with 
considerable  injury  to  the  binding  and  secretory  ligaments. 
It  is  usually  bilateral,  but   may  be   unilateral. 

Symptoms— Inability  to  close  the  mouth  is  the  pathogno- 
monic symptom.  The  jaw  will  be  locked  open  and  cannot 
be  closed  by  force.  In  the  unilateral  luxation  the  jaw  is  open 
but  is  turned  to  one  side. 

Treatment — A  piece  of  hard  wood  two  feet  long  and 
about  one-half  inch  thick,  wide  enough  to  rest  along  both 
mferior  arcades,  is  firmly  fastened  to  the  lower  jaw  (within 
the  mouth)  by  wrapping  with  strong  cord.  The  stick  thus 
adjusted  is  then  used  as  a  lever  to  depress  the  jaw  pos- 
teriorly. When  sufficient  pressure  is  brought  to  bear  the 
condyle  snaps  into  its  cavity. 

BIT  GNATHITIS. 

Synonyms — Bit  contusions.    Fractured  jaw.    Bit  sores. 

Definition — A  traumatic  inflammation  of  the  interdental 
space  of  the  lower  jaw  produced  by  bruising  with  the  bit. 

Etiology — Bit  gnathitis  is  caused  by  the  use  of  harsh  bits, 
especially  curb  bits.  The  straight  or  snaffle  bit  will  occasion- 
ally produce  the  trouble  in  horses  inclined  to  "pull"  heavily 
upon  reins  in  the  hands  of  a  powerful  reinsman.  Habitual 
"pullers"  are  the  susceptible  subjects,  when  attempts  are 
made  to  control  them  by  the  use  of  harsh  riggings.  The 
condition  is  seen  most  frequently  in  the  coach  horse,  saddle 
horse,  hunter  and  polo  ponies,  and  in  the  light  harness  horsf 
that  is  difficult  to  control. 

Pathological  Anatomy — The  lesion  consists  of  an  intense 
local  stomatitis,  periostitis  and  osteitis  occurring  simultane 
ously.    The  inflammatory  action  may  be  confined  to  a  small 


ANIMAL  DENTISTRY.  215 

circumscribed  area  at  the  very  edge  of  the  jaw,  or  extend 
across  the  entire  ramus  to  the  inferior  border.  The  process 
subsides  by  the  separation  of  the  bone  from  the  soft  sur- 
rounding structures,  and  by  the  exfoliation  of  a  sequestrum 
the  size  of  which  will  vary  with  the  extent  and  severity  of  the 
pre-existing  inflammation.  Complete  division  of  the  ramus 
may  result  in  the  extremely  aggravated  forms. 

Symptoms — Tenderness  manifested  in  adjusting  the  bit, 
ptyalism,  side  reining  and  disinclination  to  "take"  the  bit  are 
prominent  symptoms.  Palpation  and  inspection  of  the  inter- 
dental space  will  reveal  a  wound  in  the  mucous  membrane. 
The  abrasion  is  usually  large  enough  to  expose  the  edge  of 
the  jaw,  which  is  easily  felt  with  the  finger.  In  other  cases 
the  mucous  membrane  may  remain  intact  with  the  exception 
of  a  small  almost  imperceptible  opening  which,  if  enlarged 
with  a  bistoury,  will  reveal  the  bare  jaw  beneath.  In  the 
early  stage,  before  the  abscess  points,  there  may  be  con- 
siderable swelling  externally  across  the  ramus,  giving  the 
appearance  of  an  external  trauma.  In  the  advanced  state  of 
the  process,  the  bare  bone  is  found  to  be  loose  and  easily 
removed.  With  this  event  the  process  terminates  and  the 
wound  heals  rapidly,  but  leaves  a  tenderness  of  the  "seat  of 
the  bit"  for  several  months. 

Treatment — Bit  gnathitis  must  be  treated  on  the  ex- 
pectant plan  until  the  exfoliating  process  is  complete,  that  is 
until  the  sequestrum  is  well  loosened.  To  prevent  the  bur- 
rowing of  pus  downward,  as  well  as  to  hurry  the  exfoliation, 
the  edge  of  the  jaw  may  be  exposed  by  a  free  longitudinal 
incision.  The  incision  is  then  kept  free  from  food  by  daily 
irrigations  until  the  sequestrum  is  sufficiently  loosened  to 
be  easily  lifted  with  a  small  lever  or  curette.  Undue  haste 
in  the  removal  of  the  sequestrum  is  harmful  by  retarding  the 
final  closure  of  the  wound.  About  five  days  after  removal 
of  the  sequestrum  the  bottom  of  the  wound  is  curetted  to 


216 


ANIMAL   DENTISTRY. 


remove   small  roughened  projections  that   might  delay   the 
cicatrization. 

DurinL;-  the  inrianiniatnry  period  and  until  the  sequestrum 
is  removed  the  hit  must  not  he  used,  unless,  when  the  wound 
is  small,  it  can  he  adjusted  at  a  safe  distance  ahove. 

OSTEOMATA  OF  THE  SUPERIOR  MAXILLA. 

Definition — A  non-intlammatory  tumefaction  on  the  su- 
perior maxillary  of  young  horses,  due  to  ohstructed  down- 
ward growth  of  the  permanent  molars. 

Etiology — This  ahnormality  occurs  chielly  over  the  fang 
of  the  third  superior  molar,  the  last  of  the  permanent  molars, 
having  temporary  predecessors  to  erupt.  At  the  period  of 
its  eruption,  three  years  old,  it  frequently  finds  its  down- 
ward course  hlocked  in  a  wxdge-shaped  space,  between  the 
second  and  fourth  molars,  which  occupy  fixed  positions  in 
the  jaws.  The  growth  of  the  tooth  in  its  blocked  position 
produces  pressure  against  the  skull  and  a  tumor  results. 

Pathological  Anatomy — Osteoma  of  the  maxilla  is  a  non- 
inflammatory growth  due  to  a  proliferation  of  bone  cells 
somewhat  loosely  arranged.  Their  macroscopic  appearance 
is  that  of  dense  cancellated  tissue,  unlike  the  osteophyte  of 
inflammatory  origin.  They  are  diffused  over  the  anterior 
end  of  the  superior  maxilla  and  are  occasionally  bilateral. 

Differential  Diagnosis — They  are  differentiated  from 
osteo-porosis  by  the  absence  of  any  general  symptoms,  the 
absence  of  any  abnormality  in  the  lower  jaw  and  by  their 
anterior  location,  and  from  growth  of  traumatic  origin  by  the 
absence  of  heat,  pain  or  swelling  of  the  soft  tissues;  from 
odontomata  by  the  age  of  the  patient. 

Symptoms   and    Treatment — (See    abnormal    eruptions, 

page  175). 

CARCINOMATA  OF  THE  PALATE. 

The  palate  of  the  horse,   opposite   the   fourth,   fifth   and 
sixth  molars,  is  frequently  the  seat  of  carcinomatous  growths. 


ANIMAL  DENTISTRY. 


217 


They  begin  by  the  appearance  of  one  or  more  malignant  look- 
ing foci,  and  gradually  invade  more  and  more  widely  into 
the  surrounding  tissues.  They  usually  perforate  the  bony 
palate  and  establish  a  free  communication  between  the 
mouth  and  nasal  cavities.  In  the  old  cases  that  are  allowed 
to  survive,  the  process  may  extend  backward  to  the  ethmoid 
and  sphenoid  bones  and  from  the  point  of  origin  through  the 
fauces  into  the  pharynx.  They  become  complicated  with  an 
offensive  catarrh  of  the  nasal  mucosa  and  with  more  or  less 


Fig.  147. 
The    Effect   of   a    Carcinoma    Beginning  at  the  Palate  of  a  Young    Horse. 

disturbance  to  the  eye.  One  case  coming  to  our  notice  ex- 
cavated a  large  opening  externally  through  the  malar  and 
lachrymal  bones  and  totally  destroyed  the  globe  of  the  eye 
and  its  appendages.  The  condition  is  of  course  incurable  and 
is  met  by  recommending  the  killing  of  the  patient.      (Fig 

I47-) 

SARCOMATA  OF  THE  MOUTH. 

Sarcomatous  growths  in  the  palate  of  the  horse  are  of 
frequent  occurrence.     They  begin  in  the  periosteum  of  the 


218 


ANIMAL  DENTISTRY. 


palate,  nsnally  in  tlie  rc^c^ion  ni  the  fifth  molar,  and  traverse 
upward  between  the  teeth  and  alon^'  the  alveolar  border. 
They  are  Ih-st  ()])ser\-e(l  by  the  aj^pearanee  of  a  diffused  swell- 
ing of  the  palate  extending  along  the  molars  and  transversely 
across  the  raphe.  They  extend  upward  into  the  alveolar 
.:avities  around  two,  three,  or  even  four  molars,  into  the 
sinuses,  and  even  produce  bulging  of  the  facial  1)ones.  The 
molars  loosen  and  fall  out  or  are  easily  extracted  with  the 
fingers,  and  their  removal  is  always  followed  by  severe 
hemorrhage.  After  the  teeth  are  removed  the  cavities  rapidly 
fill  with  sarcomatous  tissue,  which  will  bleed  profusely  wdien 
disturbed  by  mastication.  The  course  of  the  process  is  slow^ 
in  the  early  stages  but  very  rapid  after  the  teeth  have  be- 


FlG.  148. 
A  Sarcoma  of  the  Jaw  Involving  the  Entire  Molar  Arcade. 

come  seriously  involved.     They  occur  as  clinical  conditions 

in  horses  past  the  age  of  ten  years,   but  probably   escape 

notice  during  the  early  period  of  growth.    They  belong  in  the 

category  of  incurable  diseases.     The  disease   must  not  be 

designated  "osteo-sarcoma,"  a  condition  w^e  have  never  had 

the  opportunity  of  seeing  in  the  domestic  animals,  although 

its  existence  is  not  doubted.     (See  Fig.  148.) 

ACTINOMYCOSIS. 

Synonym — Lumpy  jaw. 

Definition — Actinomycosis  is  a  chronic  infectious  disease 
due  to  the  actinomyces,  characterized  by  the  formation  of  a 
neoplasm  at  the  seat  of  infection. 

Susceptible  Animals — Ox,  sheep,  swine,  horse  and  man. 
Tlie  disease  is  not  entirely  foreign  to  any  of  the  domestic 


ANIMAL  DENTISTRY. 


219 


or  wild  herbivora  and  omnivora,  and  it  has  been  produced 
experimentally  in  rodentia  and  carnivora. 

Etiology — The  cause  of  lumpy  jaw  is  the  growth  of  the 
actinomyces  in  an  infected  tissue.  The  organism  is  a 
saprophyte  of  forage,  through  which  medium  it  gains 
entrance  into  the  body  by  inhalation  into  the  air  passages 
and  by  ingestion  into  the  digestive  tract.  Eruption  of  teeth, 
dental  irregularities  and  wounds  produced  by  fibrous  forage 
produce  favorable  channels  of  entrance,  hence  the  frequency 
of  the  disease  about  the  mouth  and  pharynx.  The  organism 
is,  however,  capable  of  producing  its  pathogenicity  in  the 


"^^^ 


Fig.  148A. 
Lumpy  Jaw  in  the  Ox. 

nasal  cavities,  lungs,  stomach  and  liver  where  wounds  are 
not  etiological  factors. 

Affected  Organs — Mouth,  lips,  nostrils,  tongue,  jaws, 
salivary  glands,  Schneiderian  membrane,  velum,  pharynx, 
rumen,  omasum,  liver,  lungs,  and  mammae. 

Diagnosis — The  early  signs  of  actinomycosis  located  in 
visible  parts  of  the  body,  consist  of  the  formation  of  one  or 
more  wart-like  nodes  which  may,  when  first  noticed,  be  only 
the  size  of  a  pea.  These  nodes  contain  a  calcareous  or  case- 
ous center.  In  the  tongue  the  condition  usually  remains 
unnoticed  until  the  organ  has  become  indurated  (wooden 
tongue).     In  the  jaw  the  disease  is  first  manifested  by  the 


220 


ANIMAL  DENTISTRY. 


appearance  of  a  more  or  less  diffused  tumefaction  of  the  in- 
ferior maxilla  (lumpy  jaw)  or  by  rouudccl  exostoses.  As  the 
soft  structures  become  involved  more  and  more  by  spread- 
ing of  the  diseased  process,  the  head  may  assume  an  un^ 
sij^htly  appearance  from  the  enormity  of  the  swelling-.  The 
condition  is  further  complicated  by  dental  disorders — loosen- 


FlG.    I48B. 

Actinomycostic  Superior  Maxillary  in  the  Ox. 

jng  of  the  teeth.  In  the  pharynx  the  disease  is  manifested 
by  tumefaction  of  the  parotid  region  and  by  dysphagia  and 
dyspnoea.  Actinomycosis  of  the  lungs  and  other  internal 
structures  is  diagnosed  only  at  the  autopsy.  Symptoms  of 
organic  disorder  may  lead  a  diagnostician  to  suspect  the  ex- 


Fig.  148c. 
Actinomycostic  Inferior  Ma.xillar>'  in  the  Ox. 

istence  of  the  disease  in  districts  where  actinomycosis  is 
prevalent,  but  a  positive  diagnosis  of  it  in  the  internal  struc- 
tures is  not  possible  in  the  living  animal. 

Treatment^ — In  the  operable    actinomycotic    tumor  abla- 
tion  is   the   most   effectual   line   of   treatment.     To   further 


ANIMAL   DENTISTRY. 


221 


x~ 


5 
6- 


/ 


10 


11 


>-^i^ 


"'-l 


--8 


Fig.  149. 
Dental  Teratoma  and  Conchal  Fistula.    (Williams). 

1.  Mouth  of  the  conchal  fistula. 

2.  Bottom  of  the  fistulous  tract. 

3.  Gubernaculum  dentis. 

4.  9.     Bony  plates  from  the  temporal  bone. 

5.  The  tooth. 

6.  External  auditory  meatus. 

7.  Wall  of  the  fistulous  tract. 

8.  Petrous  temporal  bone. 

10.  Zygoma. 

11.  Temporo-maxillary  articulation. 


222  ANIMAL  DENTISTRY. 

assure  destruction  of  the  organism  the  surgical  wound  may 
l)e  treated  with  powdered  copper  sulphate  at  intervals  of  four 
to  five  days  during  the  healing  process.  The  inoperable 
tumor  on  the  surface  of  the  body  is  injected  with  a  solution 
containing  some  form  of  iodine.  Lugol's  solution,  potas- 
sium iodide,  2  per  cent,  or  tincture  of  iodine,  may  be  used  for 
this  purpose.  Internally  potassium  iodide  will  prove  bene- 
ficial. The  loose  teeth  must  be  extracted  and  the  caustic 
treatment  applied  to  the  entire  diseased  area  when  possible. 

DENTAL  TERATOMATA. 

Synonyms — Dentigerous  cysts,  dental  cysts,  mastoid 
fistulae. 

Definition — An  abnormality  of  early  embryonic  origin  in 
which  one  or  two  teeth  develop  on  the  temporal  bones  near 
the  base  of  the  ear.  It  is  a  common  abnormality  of  solipeds 
but  occurs  occasionally  in  other  mammals. 

Etiology — The  cause  of  dental  teratomata  is  found  in  an 
aberration  of  the  embryonic  evolution  of  the  teeth,  guttural 
pouch  and  external  ear,  the  mechanism  of  which  is  so  compli- 
cated as  to  be  susceptible  to  variations.  The  condition  is 
closely  allied  to  conchal  fistula,  with  which  it  is  frequently 
associated. 

Symptoms — Dental  teratomata  of  the  mastoid  region 
exist  from  the  time  of  birth,  although  they  may  escape  detec- 
tion until  maturity.  They  appear  at  the  surface  in  the  form 
of  a  fistulous  opening  below  the  base  of  the  ear  or  along  the 
margin  of  the  conchal  cartilage,  discharging  a  limited  quan- 
tity of  a  viscid  mucoid  secretion.  The  channel  is  lined  w'ith 
a  well  organized  epithelial  membrane  continuous  with  the 
skin  at  the  orifice.  They  are  susceptible  to  pathological  con- 
ditions which  may  for  the  first  time  direct  attention  to  their 
presence.    When  they  become  infected  the  resulting  osteitis, 


ANIMAL  DENTISTRY. 


223 


periostitis  and  dentitis  augment  the  discharge,  and  change 
its  character  into  a  fetid,  purulent  secretion,  and  the  region 
becomes  painful  to  the  touch. 

When  opened  by  incision  the  cyst  is  found  to  contain  a 
tooth  or  two,  which  vary  from  the  size  of  a  hazel  nut  to  that 
of  a  full  sized  molar.     The  smaller    ones  are  quite  round, 


i^'  j' 


1j    7. 


V3 


o 


Fig.  150. 
Two  Teeth   Removed   from   the   Squamous  Temporal   Bone   of  a   Clydesdale 

Mare. 

while  the  larger  ones  assume  the  typical  tooth  dimensions. 

Treatment — The  patient  is  placed  in  the  lateral  recum- 
bent position,  preferably  under  the  influences  of  an  anaesthe- 
tic. A  liberal  incision  is  made  over  the  tumefaction  so  as  to 
expose  the  hard  object  within.  This  will  always  be  foimd  to 
be  a  tooth.  When    a  part  projects  it  can  be  extracted  with 


224  ANIMAL  DENTISTRY. 

an  ordinary  Wolf  tooth  focej^s.  hut  fre(|ucntly  the  surround- 
ings will  require  chiseling  to  first  loosen  it  from  its  cavity. 
When  removed  the  cavity  must  be  searched  for  a  possible 
second  tooth,  and  if  the  canal  is  long,  as  in  the  case  of  concha! 
fistula,  the  entire  lining  must  be  resected  to  prevent  a  per- 
petual discharge. 

DENTAL  FISTULAE. 

Definition — A  fistulous  tract  related  to  the  teeth,  ex- 
tending from  within  the  mouth  to  the  outer  surface  of  the 
jaw. 

Etiology — Dental  fistulae  result  from  the  outward  point- 
ing of  an  abcess  accompanying  a  decayed  molar.  The  en- 
trance channel  may  be  the  infundibula  or  alveolar  perios- 
teum. In  the  upper  jaw  they  are  occasionally  caused  by 
defective  gums  admitting  food  along  the  external  surface 
of  the  second  or  third  molar,  in  the  grooves  between  the 
prominent  longitudinal  ridges  which  exist  on  these  teeth, 
and  in  the  lower  jaw  they  may  in  rare  instances  result  from 
external  violence.  And  again,  sequestra  of  bones  allowed 
to  remain  between  the  alveolar  plates  after  the  repulsion  of 
teeth  may  produce  a  chronic  fistulous  opening. 

Pathological  Anatomy — In  addition  to  the  lesions  ac- 
companying a  decayed  molar  (see  page  152)  the  dental  fis- 
tula is  nothing  more  than  a  tract  through  the  bone  from  the 
apex  of  the  tooth  to  the  surface  of  the  jaw. 

Symptoms — They  are  seen  most  frequently  on  the  lower 
jaw  opposite  the  apex  of  the  second,  third,  fourth,  fifth  and 
sixth  molars.  In  the  upper  jaw  the  second  and  third  molars 
are  the  teeth  usually  responsible  for  the  condition.  Thev 
appear  as  small  openings,  always  near  the  border  of  the  jaw. 
which  discharge  a  limited  amount  of  pus.  In  the  old  case 
the  skin  Is  drawn  inward  by  the  process  of  cicatrization.  The 
jaw  around  the  offending  molar  is  thickened  to  a  perceptible 


ANIMAL  DENTISTRY. 


225 


extent.  The  diagnosis  is  confirmed  by  an  examination  of  the 
dental  arcade.  When  the  tract  is  direct  a  small  probe  may 
be  passed  from  the  external  opening  to  the  mouth,  but  ordin- 


FlG.    ISOA. 

Inferior  Molar  Responsible  for  a  Fistula  of  the  Jaw  in  a  7- Year-Old  Horse. 

arily  it  pursues  a  tortuous  course  through  the  bone  and 
comes  to  the  surface  at  a  point  more  or  less  remote  from  the 
affected  tooth. 

Treatment — The  treatment  of  the  dental  fistula  should 


226  ANIMAL  DENTISTRY. 

first  be  limited  to  the  extraction  of  the  offending  molar  with 
the  forceps.  If  after  four  weeks  the  tract  still  exists  the 
skull  plate  around  the  opening  is  trephined  and  the  tract 
well  curetted  along  its  course  into  the  alveolar  cavity. 

TRAUMATIC  STOMATITIS. 

Definition — Stomatitis  signifies  inflammation  of  the 
mucous  membrane  of  the  mouth. 

Etiology — Primary,  traumatic  stomatitis  is  a  common 
disease  of  all  the  domestic  animals.  It  is  seen  in  the  most 
aggravated  forms  from  the  accidental  ingestion  of  irri- 
tants and  from  the  administration  of  irritating  medicines. 
Among  the  other  causes  are  dental  irregularities,  severe  bits, 
traction  on  the  tongue  and  the  prehension  of  sharp  objects. 
But  in  these  instances  the  inflammation  is  of  a  circumscribed 
rather  than  a  diffused  character. 

The  mucosa  of  herbivora  is  well  protected  against 
wounding  by  masticating  coarse  food.  Beards  of  cereals  will, 
however,  occasionally  penetrate  through  it  around  the  an- 
terior portion  of  the  mouth  and  produce  an  alarming 
stomatitis  simultaneously  in  a  number  of  animals  before  the 
cause  is  discovered. 

Pathological  Anatomy — A  simple  inflammatory  process 
promptly  terminating  in  resolution.  Purulent,  catarrhal  or 
necrotic  inflammations  of  the  mouth  are  rare.  The  severity 
and  extent  depend,  therefore,  upon  the  trauma. 

Symptoms — Ptyalism,  champing  the  jaws,  disturbed  pre- 
hension and  mastication  and  a  disinclination  to  eat  are  the 
principal  symptoms.  The  mucous  membrane  is  sensitive  to 
the  touch  and  the  patient  will  resent  examinations.  On 
inspection  there  will  be  redness  and  in  the  severe  case 
desquamation  of  the  superior  surface  of  the  tongue. 

Treatment — Stomatitis  is  not  a  serious  disease.  Removal 
of  the  cause,  the  administration  of  soft  diet,  and  demulcent 


ANIMAL    DENTISTRY.  227 

or  mild,  astringent  solutions,  is  the  only  necessary  treat- 
ment. A  useful  mouth  wash  for  the  treatment  of  either  cir- 
cumscribed or  diffused  stomatitis  is : 

R. 

Alum 

Sodii  boras   aa 30 

Spirits  gaultheria   10 

Aqua  q.s.  ad 480 

M  et  sig. 

Inject  freely  into  the 
mouth  three  to  four  times 
daily. 

STOMATITIS,  INFECTIOUS. 

Synonyms — Contagious  pustular  stomatitis ;  aphthous 
stomatitis;  contagious  aphtha. 

Definition — An  infectious  inflammatory  condition  of  the 
buccal  mucosa  characterized  by  the  formation  of  a  multi- 
plicity of  pustules. 

Etiology — Infectious  stomatitis  evidently  owes  its  ex- 
istence to  a  specific  virus,  the  identity  of  which  is  unknown. 

Symptoms — Contagious  aphtha  usually  occurs  simultane- 
ously in  a  number  of  horses  belonging  to  the  same  stable. 
Outbreaks  often  occur  at  race  tracks,  fairs  or  sale  stables  in 
which  few  of  the  exposed  animals  escape.  The  virus  is 
evidently  carried  into  the  mouth  through  the  medium  of 
watering  places,  pails,  cleaning  utensils,  bridles,  etc.  The 
first  clinical  symptom  observed  is  ptyalism  and  slight  anor- 
exia, which  is  followed  by  the  rapid  development  of  many 
small  pimples  which  point  and  leave  an  ulcer.  In  some  cases 
the  skin  around  the  commissures  of  the  mouth  becomes  in- 
fected and  leaves  behind  a  depigmentated  spot  at  the  seat  of 
each  ulcer. 

Treatment — Infectious  stomatitis  runs  a  favorable  course 


228 


ANIMAL   DENTISTRY, 


-   S 


t. 


m 


ANIMAL   DENTISTRY.  229 

in  every  case  and  it  recjuires  1)nt  little  treatment.  Preventive 
measures  are  the  most  important  and  these  consist  of  isola- 
tion of  the  affected  animals  and  the  disinfection  of  the 
infected  stalls,  implements,  feed  boxes,  etc. 

(For  a  more  complete  description  see  works  on  General 
Medicine.) 

ULCERATIVE  GINGIVITIS  OF  DOGS. 

Definition — Ulcerative  gingivitis  is  a  disease  of  young 
carnivorous  animals  Ijeginning  as  an  inflammation  of  the 
gums.  It  however  spreads  rapidly  to  the  surrounding  mucosa, 
alveolar  periosteum  and  jaw. 

Etiology — The  cause  of  the  disease  is  undoubtedly  the 
propagation  of  microbes  which  habitually  inhabit  the  mouth 
of  meat  eating  animals,  and  which  become  pathogenic  under 
the  influence  of  a  lowered  vitality  of  the  animal.  Attempts 
to  isolate  a  specific  microbe  have  thus  far  failed. 

Symptoms — Foetid  breath  occurring  simultaneously 
with  red  or  bluish  red  gums  are  the  first  distinguishing 
symptoms.  The  teeth  are  found  to  be  coated  with  an  excess 
of  tartar  around  the  gingival  margin,  and  in  the  more  ad- 
vanced stage  they  are  loosened  and  easily  extracted.  The 
gums,  cheeks  and  tongue  may  become  the  seat  of  numerous 
ulcers  as  the  disease  progresses,  but  often  this  feature  is 
wanting.  The  process  usually  terminates  favorably  or  fatally 
in  from  one  to  two  weeks,  according  to  its  severity  and  the 
vitality  of  the  patient,  or  it  may  become  chronic  and  last  as 
long  as  four  to  five  weeks. 

Treatment — The  first  treatment  should  consist  of  ex- 
tracting the  loose  teeth  and  removing,  with  the  curette,  all 
of  the  tartar  from  the  stable  ones.  The  mouth  is  then 
washed  freely  with  mild  antiseptics,  boric  acid  and  borax 
water  being  the  most  appropriate  ones  for  the  purpocf.  A 
50  per  cent  solution  of  tincture  of  iodine  painted  carefully 


230  ANLMAL   DENTISTRY. 

over  the  gums,  ulcers  and  vacant  tooth  cavities  after  the 
saliva  has  been  wiped  away  will  frequently  arrest  the  pro- 
cess, and  would  undoubtedly  prove  a  specific  if  its  toxicity 
did  not  prevent  its  repetition. 

RETENTION  CYSTS. 

Besides  the  large  cyst  that  occurs  in  the  fraenum  of  the 
tongue  (ranula),  the  mucous  membrane  of  the  mouth  of 
horses  is  occasionally  the  seat  of  mucoid  cysts  varying  from 
the  size  of  a  millet  seed  to  that  of  a  pea.  The  common 
location  is  around  the  commissures,  either  superiorly  or 
inferiorly.  Anatomically  they  consist  of  a  dilated  mucous 
follicle  resulting  from  an  obstructed  outlet.  They  are  per- 
fectly benign  and  yield  to  evacuation  of  the  contents  by 
incision. 

TUMORS  OF  THE  MUCOUS  MEMBRANE  OF  THE 

MOUTH. 

The  following  is  an  enumeration  of  the  various  tumors 
affecting  the  mucous  membrane  of  the  mouth : 
(i)   Actinomycosis,  see  page  218. 

(2)  Sarcoma,  see  page  218. 

(3)  Carcinoma,  see  page  217. 

(4)  Ranula,  see  page  250. 

(5)  Retention  cysts,  see  page  230. 

LAMPAS. 

Definition — Tumefaction  of  the  hard  palate  just  behind 
the  superior  incisor  arcade. 

Etiology — Lampas  is  a  physiological  condition  occurring 
from  dental  nutrition  during  the  growth  of  the  teeth.  It 
occurs  at  a  time  when  the  crowns  of  the  teeth  are  still  too 
short  to  overlap  the  first  bars  of  the  palate.     In  old  horses 


ANIMAL    DENTISTRY.  231 

the  palate  may  project  beyond  the  level  of  the  arcade  from 
wear  of  the  incisors,  when  the  latter  are  soft  in  texture. 

Symptoms— Tumefaction  and  redness  of  the  first  bars  of 
the  palate.  Sensitiveness  is  not  a  characteristic  feature.  The 
bars  project  to  the  level  or  below  the  tables  of  the  incisors. 

Treatment — The  popular  impression  that  lampas  is 
inimical  to  the  welfare  of  an  animal  necessitates  the  appli- 
cation of  efforts  to  diminish  the  size  of  the  tumefaction. 
This  is  done  by  scarification  and  actual  cautery.  The  latter 
is  the  effectual  method.  The  thermo-cautery  is  par  excel- 
lence the  neatest  method  of  satisfying  the  popular  prejudice 
against  them.  Confine  the  horse  with  the  dental  halter  and 
twitch,  and  elevate  the  head.  Pass  a  round  stick  through 
the  interdental  space  and  hold  it,  together  with  the  tongue, 
in  the  left  hand.  Hold  the  mouth  open  by  downward  pres- 
sure upon  the  stick  and  tongue  and  keep  the  upper  lip 
elevated  with  the  twitch,  and  then  with  the  right  hand  caut- 
erize the  first  two  or  three  bars  until  they  shrink  below  the 
table  level. 

SECONDARY  CHRONIC  NASAL  CATARRH. 

Synonyms — Chronic  nasal  catarrh.  Unilateral  chronic 
rhinitis.  Nasal  gleet.  Ozena.  Purulent  accumulations  in 
the  facial  sinuses. 

Etiology — Primary  chronic  nasal  catarrh  is  a  rare  disease 
in  the  herbivorous  animals.  The  chronic  nasal  catarrh  of 
the  horse  and  ox  has  its  origin  in  the  surrounding  structures 
and  hence  can  only  be  described  as  a  secondary  condition. 
The  primary  lesion  can  usually  be  found  in  the  superior 
dental  arcades.  Decayed  teeth,  usually  the  fourth  superior 
molar,  are  responsible  for  95  per  cent  of  the  cases.  Alveolo- 
nasal  fistula,  fractures,  foreign  bodies,  parasites,  glanders, 
timors  and  chronic  bronchitis  constitute  the  primary  lesions 
ol  the  other  five  per  cent. 


232  ANIMAL   DENTISTRY. 

Pathological  Anatomy — The  features  of  a  typical  case 
are:  Purulent  or  niuco-purulcnt  catarrh  of  the  affected  side, 
accumulation  of  the  secretions  in  the  recesses  of  the  sinuses, 
over-filling  of  the  sinuses  and  bulging-  of  the  bones,  pressure 
necrosis  of  the  turbinated  bones  and  the  septa  of  the  sinuses, 
outward  discharge  of  the  secretion,  alveolar  periostitis  and 
necrosis  of  a  molar. 

Diagnosis — The  pathognomonic  symptom  is  the  chronic, 
fetid,  unilateral  discharge  from  the  nostril  occurring  simul- 
taneously with  a  dental  disorder  on  the  affected  side.  The 
decayed  tooth  in  the  early  stage  of  decay  may  be  difificult 
to  locate,  but  owing  to  the  frequency  of  this  cause  a  special 
examination  of  the  superior  dental  arcade  must  be  made 
before  the  other  causes  are  given  any  consideration.  Nega- 
tive results  from  the  palpation  or  inspection  of  the  teeth 
with  or  without  a  mouth  speculum  is  not  sufficient  reason 
to  exclude  the  decayed  tooth  as  a  cause.  The  patient  must 
be  placed  in  a  recumbent  position,  a  mouth  speculum  ad- 
justed, and  by  the  aid  of  good  light  each  tooth,  beginning 
with  the  fourth,  must  be  carefully  examined  with  a  sharp 
steel  pick.  Diseased  teeth  which  would  otherwise  have 
escaped  notice  are  in  this  manner  found  to  have  one  or  both 
infundibula  admitting  food  into  the  pulp  cavity.  When  the 
teeth  have  been  excluded  by  this  circumspect  investigation 
the  attention  may  be  directed  to  the  other  possible  causes, 
but  in  no  case  of  chronic  catarrh  must  the  examination  of  the 
teeth  be  omitted.  Even  in  the  bilateral  catarrhs  the  lesion 
may  be  found  on  one  side  of  the  head  and  in  many  instances 
decayed  teeth  co-exist  on  both  sides  of  the  head. 

Differential  Diagnosis — Nasal  gleet  is  differentiated  from 
glanders  by  the  mallein  test ;  from  guttural  pouch  catarrh 
by  the  profuse  discharge  during  mastication  in  the  latter 
disease;  from  bronchitis  by  the  absence  of  cough  and  con- 
stitutional disturbance,  and  by  the  frothy  bubbles  usually 


ANIMAL   DENTISTRY. 


233 


contained  in  secretion  coming  from  the  lower  air  passages. 
Treatment — The  treatment  includes:  (i)  Removal  of 
the  primary  lesion;  (2)  evacuation  of  the  accumulated  secre- 
tions from  the  sinuses,  and,  (3)  irrigation  of  the  diseased 
mucous  membrane.  Internal  medication  is  of  little  value  in 
terminating  nasal  catarrh.  Local  applications  in  the  form 
of  douches  are  equally  useless. 


Fig.  151. 
Correct  Locations  of  Openings  to  Perfectly  Drain  the  Sinuses  of  a  Horse's 
Head.  The  upper  opening  drains  the  frontal  sinus  outward,  and  by  per- 
forating its  floor  in  the  turbinated  bone,  it  also  drains  the  sinus  into  the 
nasal  cavity.  The  dotted  line  on  the  lower  opening  shows  the  direction 
to  elongate  the  orifice  when  a  tooth  is  to  be  repulsed. 

OPERATION  OF  TREPHINING  THE  SKULL  FOR  NASAL 

CATARRH. 

Equipment — ^Two  scalpels,  three-fourths  inch  circular  tre- 
phine, one  inch  circular  trephine,  dissecting  forceps,  chisel, 
artery  forcep,  needles  and  thread  (punches  and  mallet  if 
teeth  are  to  be  repulsed),  razor,  wadding  of  cotton  or  oakum 
and  antiseptics. 


234 


ANIMAL   DENTISTRY. 


Restraint — Horses  may  be  lrcpliiiu'<l  in  tlie  standiiii;-  po- 
sition with  the  dental  halter  and  Iwitcli.  \\'hen  teeth  are  to 
be  repulsed  or  when  any  cliiselinL;"  of  the  bone  is  necessary 
the  recumbent  position  is  essential. 


y 

Fig.  15 1  a. 
Plain  Circular  Trephine. 

ist  Step — Clip,  shave  and  disinfect  the  space  intervening 
between  the  maxillary  spine  and  longitudinal  suture  of  the 
nasal  bones. 

2nd  Step — First  open  the  maxillary  sinus  about  one  inch 


Fig.   15  IB. 
Assorted  Trephines  and  Tooth  Drills,  with  Brace. 

from  its  external  border  and  one  inch  from  the  anterior  ex- 
tremity, but  vary  in  the  antro-posterior  direction  according 
to  tooth  to  be  repulsed. 

3rd  Step — Make  a  T-shaped  incision  through  the  skin 
with  the  base  of  the  T  pointing  to  the  median  line  of  the 
head. 


ANIMAL   DENTISTRY. 


235 


4th  Step — Dissect  the  muscle  and  connective  tissue  from 
the  bone  and  arrest  the  hemorrhage. 

5th  Step — Cut  a  circular  ring  in  the  periosteum  slightly 
larger  than  the  diameter  of  the  trephine  to  prevent  tearing 
it  beyond  the  area  of  the  circle. 

6th  Step — Remove  the  skull  plate  with  the  three-fourths 
inch  trephine. 

7th  Step — If  a  tooth  is  to  be  repulsed,  enlarge  the  open- 


FiG.  152. 
Surgical   Areas  of  the   Sinuses. 

A,  A.     Maxillary  sinuses. 

B,  B.     Frontal  sinuses. 

ing  toward  the  median  line  of  the  head  with  chisel  and 
mallet,  so  that  the  punch  can  be  placed  on  a  straight  line 
with  the  tooth. 

8th  Step — (See  repulsion  of  teeth,  page  161). 

9th  Step — Open  the  skull  with  the  one-inch  trephine,  at  a 
point  4  to  5  centimeters  obliquely  downward  and  inward 
from  the  nasal  canthus  .     (See  Fig.  151.) 

loth  Step — Break  down  the  thin,  bony  septa  with  the 


236  ANIMAL    DENTISTRY. 

inii^crs  so  as  to  freely  drain  the  frontal  sinus  into  the  maxil- 
lary sinus  and  nasal  eax'ity. 

nth  Step — lunpty  and  irri,L;ate  the  sinuses  in  the  stand- 
ing position  and  wad  the  openings  with  oakum  or  cotton. 

I2th  Step — Suture  the  transverse  incision  of  the  T-shaped 
wound,  leaving  the  longitudinal  one  for  wadding  and  drain- 
age. 

After-care — Irrigate  with  3  per  cent  zinc  sulphate  solu- 
tion daily.  Prevent  food  from  entering  the  cavity  by  wad- 
ding the  tooth  cavity. 

Note — The  two  openings  above  referred  to  are  the  only 
ones  necessary  to  drain  the  sinuses  of  the  horse's  head. 
Openings  higher  up  along  the  frontal  sinus  serve  no  useful 
purpose.  The  important  feature  of  the  operation  is  to  drain 
the  sinuses  into  the  nasal  cavity  by  breaking  down  the 
bony  septa.  Unless  there  is  free  flow  from  the  upper  opening 
to  the  nostrils  the  trephining  operation  for  nasal  catarrh  is 
a  useless  procedure. 

CHRONIC  PERFORATION  OF  THE  SKULL. 

Definition — Under  this  head  we  include  the  openings  of 
the  skull  covering  the  facial  sinuses  or  nasal  cavities,  that 
persist  after  the  regenerative  process  has  ceased. 

Etiology — The  chronic  or  peristent  perforations  of  the 
skull  of  horses  follow  large  surgical  openings  necessary  to 
remove  nasal  tumors,  severe  contusions  of  the  skin  compli- 
cated with  comminuted  fractures  of  the  skull  plate,  attended 
with  sloughing  of  the  injured  area,  and  circular  trephine 
openings  followed  by  necrosis  of  the  surrounding  bone.  The 
sequel  is  most  liable  to  occur  in  old  horses  from  the  dimin- 
ished nutrition  of  the  bone  tissue  and  periosteum.  It  is 
seldom  seen  in  young  animals,  except  in  accidental  perfora- 
tion of  large  dimensions,  accompanied  with  loss  of  a  large 
area    of    common    integument.      Surgical    perforations,    al- 


ANIMAL  DENTISTRY. 


237 


though  quite  large,  will  always  heal  eventually  in  the  young 
horse  but  may  threaten  to  become  permanent  in  horses  past 
the  age  of  eighteen  years.  The  most  aggravated  forms  occur 
from  comminuted  fractures. 


Fig.  153. 
Prof.    Edw.    Merillat's    Operation    for    Closing    Chronic    Skull    Perforations. 

A.  3rd  step  of  operation. 

I,  2.     "Melon  slice"  resection  of  the  skin.     See  description. 

B.  4th  step  of  operation.     See  description. 

C.  6th  step  of  operation.     See  description. 

Treatment — Large  perforations  accompanied  with    loss 
of  considerable  skin  may  be  incurable,  but  when  the  orifice 


238  ANIMAL  DENTISTRY. 

IS  of  nominnl  dimensions  its  closure  is  effected  by  tlie  fol- 
lowing operative  intervention  : 

ist  Step — Secure  the  subject  in  the  lateral  recumbent 
position  without  anaesthesia. 

2nd  Step — Shave  the  hair  from  the  surgical  area  and  dis- 
infect with  mercuric  chloride  solution  1-500. 

3rd  Step — (big.  153A.)  Make  a  "melon-slice"  resection  of 
the  skin,  extending  above  and  below  the  orifice,  so  as  to 
include  the  orifice  within  its  widest  portion. 

4th  Step — (Fig.  153B.)  Make  a  longitudinal  incision  (Fig. 
153B.  3.  3.)  through  the  skin  on  each  side  of  and  about  one 
inch  from  the  orifice,  extending  the  entire  length  of  the  re- 
sected  skin. 

5th  Step — Loosen  from  the  bone  all  of  the  skin  between 
the  longitudinal  incisions. 

6th  Step — (Fig.  153C.  5.)  Suture  the  "melon-slice" 
wound  with  interrupted  stitches,  1)ringing  the  raw  edges  into 
perfect  apposition. 

7th  Step — Protect  the  whole  area  with  a  clay  dressing. 

After-care — Maintain  perfect  protection  during  eight  days 
and  then  remove  the  sutures.  Apply  astringent  lotions  to 
the  gaping  longitudinal  wounds  (Fig.  153C.  4.  4.)  which  will 
heal  by  granulations. 

APPLICATION  OF  GUTTA  PERCHA  PLUGS. 

An  artificial  filling  for  the  vacant  alveolar  cavity  subse- 
quent to  the  extraction  of  molars  is  indicated  w'hen  the 
cavity  refuses  to  close  and  thereby  admits  food  into  the 
nasal  cavities  or  sinuses,  in  chronic  dento-nasal  fistula  and 
in  wadding  a  recently  made  tooth  cavity  that  cannot  receive 
daily  attention. 

The  filling  suitable  for  this  purpose  is  a  gutta  percha 
mixture  known  to  the  human  dentist  as  "temporary  stop- 


ANIMAL  DENTISTRY  239 

ping."  It  is  hard  at  the  temperature  of  the  body  but  readily 
becomes  pliable  with  heat. 

Modus  Operandi — Soften  a  liberal  amount  of  the  filling 
in  hot  water  and  roll  it  into  an  egg-shaped  mass,  larger  than 
the  cavity  to  be  filled;  then,  with  the  aid  of  a  speculum  to 
open  the  mouth,  force  the  mass  into  the  cavity  to  mold  it 
to  the  proper  shape  and  dimensions.  Then  remove  it  and 
trim  off  the  superfluous  portion,  re-heat  and  re-adjust  to  the 
cavity,  leaving  its  exposed  end  beneath  the  table  level  of 
the  arcade. 

The  gutta  percha  plugs  should  reach  beyond  the  alveolar 
margin,  but  not  to  the  bottom  of  the  alveolar  cavity,  and 
to  prevent  disturbance  from  mastication  the  opposing  crown 
should  be  removed  with  the  claw-cutter.     (Fig.  loo.) 

When  applied  as  temporary  filling  it  should  be  removed 
after  five  or  six  days  to  clean  the  cavity  of  accumulated 
secretions,  and  then  be  readjusted  for  one  week  more,  at 
w'hich  time  a  tooth  cavity  is  usually  safely  filled. 

CRIBBING  AND  WIND-SUCKING. 

Definition — Cribbing  and  wind-sucking  are  identical,  the 
latter  being  an  aggravated  form  of  the  former.  Cribbing 
may  be  defined  as  a  pertinacious  habit  of  the  horse,  charac- 
terized by  attempts  to  ingest  air,  while  wnnd-sucking  may  be 
defined  as  the  same  habit  in  wdiich  the  attempt  is  successful. 

Etiology — The  actual  cause  of  cribbing  is  yet  to  be  satis- 
factorily demonstrated.  Idleness  and  the  empty  manger  are 
circumstances  generally  accepted  as  favoring  the  acquire- 
ment of  the  habit.  Nervousness,  gastric  indigestion  and  ob- 
scure neuroses,  are  also  mentioned  among  the  possible  etio- 
logical factors.  These  assertions  are  based  only  upon  specu- 
lation, and  are  doubted  most  by  those  who  have  had  the 
widest   range   of  observation.     It  may,   however,   be   safely 


240 


ANIMAL  DENTISTRY. 


Stated  that  the  hal)it  is  one  of  doniestication,  a  sta1)le  haljit 
or  pastime  having-  its  origin  in  some  unknown  cause. 

Symptoms — Grasping  an  object  with  the  teeth,  contrac- 
ting the  inferior  cervical  muscles,  and  uttering  the  character- 
istic grunt  consecutively,  is  the  clinical  picture  of  the  typical 
cribber.  Some  subjects  follow  this  ])henomena  by  the  de- 
glutition of  a  considerable  (|uantily  of  air  at  each  attempt, 
until  marked  tympany  of  the  abdomen  becomes  apparent. 
Others  again  succeed  in  the  deglutition  without  grasping  an 
object  with  the  teeth. 


Fk;.   T53A. 
The   Mouth   of  a   Young  Cribber. 

Treatment — T\\q  application  of  a  wide  leather  strap 
tightly  around  the  throat  will  prevent  the  ingestion  of  air 
and  diminish  in  nund)er  the  attempts  at  cribbing.  If  the 
strap  is  equipped  with  tacks  that  will  prick  the  throat  when 
the  attempt  is  made  the  cribbing  will  cease  while  the  strap 
is  in  place.  A  second  method  consists  of  removing  from  the 
stall  all  objects  that  can  be  grasped  wnth  the  teeth. 

The  surgical  intervention  once  recommended,  consisting 
of  a  myotomy  of  the  sterno-maxillary  muscle  in  the  upper 
third  of  the  cervical  region,  has  become  obsolete  through 
the  revelation  of  its  uselessness  as  a  permanent  remedy. 


ANIMAL  DENTISTRY.  241 

The  pertinacity  of  the  cribbing  habit  was  demonstrated 

by  I\Ir.  A ,  of  Des  Plaines,  111.,  in  the  case  of  a  large 

Shetland  pony  that  acquired  the  habit  at  the  age  of  three 
years.  This  pony  was  confined  in  a  polished  hardwood  cage 
with  the  walls  inclined  at  an  angle  of  forty-five  degrees  from 
above  downwards  and  outwards,  for  three  years,  during 
which  time  special  care  was  taken  to  prevent  any  contact 
with  objects  that  could  be  touched  with  the  teeth.  At  the 
end  of  three  years  it  was  experimentally  placed  into  a  stall 
with  a  manger.  In  less  than  ten  seconds  the  cribbing  begun 
and  continued  until  returned  to  the  hardwood  cage. 

HABITUAL  PTYALISM. 

Synonym — Slobbering. 

Definition — A  habit  of  carriage  horses  characterized  by 
an  excessive  flow  of  saliva  from  the  mouth  while  driving. 

Etiology — Habitual  ptyalism  of  carriage  horses  is  caused 
by  the  abnormal  curbing  of  the  neck  in  horses  inclined  to 
"pull"  heavily  upon  the  reins.  The  position  of  the  head  as- 
sumed under  such  circumstances  prevents  the  free  degluti- 
tion of  the  saliva  secreted,  which  in  the  "pulling  horse"  is 
always  excessive.  Besides,  the  mind  of  the  "pulling"  car- 
riage horse  is  so  occupied  wnth  the  bit  that  no  deglutition 
is  attempted. 

Ptyalism  is  also  caused  by  sensitiveness  of  the  mouth, 
wounds,  bit  gnathitis,  and  other  forms  of  stomatitis,  but 
these  causes  constitute  an  entirely  different  entity  than  that 
referred  to  in  this  paragraph. 

Symptoms — An  excessive  flow  of  saliva  while  driving  in 
the  absence  of  any  lesion  of  the  mouth  determines  a  case  of 
habitual  ptyalism.  The  secretion  is  churned  into  a  stringy 
froth,  and  is  blown  by  the  wind  over  the  harness,  horse,  car- 
riage and  even  the  coachman.  There  is  also  a  tendency  to- 
wards "champing"  the  bit  when  the  reins  are  relaxed. 


242  ANIMAL    DENTISTRY. 

Treatment — In  the  treatment  of  ptyalism  of  carria^^e 
horses,  the  first  requisite  is  to  remove  all  dental  irrei;ulari- 
ties  that  would  tend  to  provoke  a  flow  of  saliva  Ijy  irritating 
the  buccal  surface.  The  front  molars  must  especially  be 
well  rounded.  Wounds  of  the  interdental  space  must  be 
healed  and  wolf  teeth  extracted.  The  attention  must  then 
be  directed  to  the  bitting.  The  bridoon  is  removed  and 
the  head  is  checked  with  an  overdraw  passing-  beneath  the 
chin.  The  reins  are  placed  in  the  "cheek"  or  ''lialf-cheek" 
loop  of  the  curb  bit;  or,  if  the  horse  cannot  be  managed  thus, 
a  rubber  cover  is  placed  over  the  bit  and  the  rein  attached 
to  the  middle  or  lower  bar.     The  bridle  is  fitted  neatly  so  as 


Fig.  154. 
The  Best  Bit  for  a  Side  Pulling  Light  Harness  Horse. 

to  bring  the  bit  to  a  comfortable  position  near  the  inferior 
molars.  "Dropping  the  bit"  a  habit  of  coachmen  to  gain 
advantage  of  a  "pulling"  horse  must  be  avoided.  And  finally, 
by  patient  "schooling,"  the  horse  must  be  taught  to  drive 
with  a  "light  line." 

SIDE  REINING. 

Definition — A  habit  of  driving  horses  consisting  of  con- 
stant inclination  to  carry  the  head  to  one  side  of  the  median 
line  of  the  body. 

Etiology — The  habit  of  side  reining  is  due  to  an  ingenious 
"ttempt  to  take  advantage  of  the  reinsman  by  placing  the 


ANIMAL    DENTISTRY. 


243 


head  in  a  more  advantageous  position  for  leverage.  Such 
animals  often  have  serious  lesions  of  the  jav^s,  but  these  are 
effects  rather  tiian  causes  of  the  habit.  The  habit  is  often 
acquired  by  driving  an  ambitious,  prompt  horse  with  a 
"loafer." 

The  horse  that  drives  on  but  one  line  without  pulling 
heavily  and  shifts  gradually  to  one  side  of  the  street  belongs 
to  an  entirely  different  class.     In  this  incident  the  cause  is 


Fig.  155. 


Fig.  156. 
The  suitable  bit  to  equip  with  the 
flexible  rubber  hose.     See 
description  below. 


Fig.  157. 

Tongue  Lolling  Bits. 

A.  Port   bit. 

B.  Spoon  bit. 

C.  Combined  snaffle  and  overcheck  bit. 

always  due  to  some  defect  in  the  locomotory  apparatus. 
Spavin  or  other  slight  painful  condition  of  the  hind  extremity 
is  the  usual  cause  of  this  defect. 

Treatment — The  side  reining  horse  must  first  be  treated 
for  defects  of  the  teeth  and  lesions  of  the  interdental  space. 


244  ANIMAL   DENTISTRY. 

The  first  molars  must  be  well  rounded  to  prevent  buccal 
wounds.  The  bit  is  then  kept  on  a  strai.G:ht  line  with  the  jaws 
by  means  of  washers  fastened  inside  the  rings.  A  com- 
fortable check  is  used,  and  the  horse  is  driven  only  with  one 
well  mated  in  promptness. 

HABITUAL  PROTRUSION  OF  THE  TONGUE. 

Synonym — Tongue  lolling. 

Definition — The  habit  of  extending  the  end  of  the  tongue 
from  the  commissure  of  the  mouth  while  driving. 

Etiology — The  habit  may  be  first  acquired  in  an  attempt 
to  protect  an  abrasion  of  the  mouth  from  further  injury,  but 
its  continuation  is  due  to  the  relief  to  the  respirations.  When 
the  tongue  is  dropped  from  the  fauces  the  lumen  of  the 
pharynx  is  increased  and  the  respirations  are  facilitated  suf- 
ficiently to  induce  a  continuation  of  the  habit.  Paralysis 
of  the  tongue,  in  which  retraction  is  impossible,  is  entirely 
another  condition,  occurring  as  a  result  of  progressive  bul- 
bar paralysis — a  fatal  disease. 

Treatment — Dental  irregularities  must  be  corrected  and 
the  head  while  driving  must  be  elevated  with  the  overdraw 
check  to  bring  the  air  passages  toward  a  straight  line.  The 
mouth  may  be  closed  with  a  nose  band  attached  to  the  bridle. 
Attaching  the  check  bit  to  the  main  bit  by  means  of  a  flexible 
rubber  hose,  will  frequently  prevent  the  habit. 

When  these  measures  fail,  amputation  of  the  tongue  is 
the  only  recourse. 

OPERATION  OF  AMPUTATION  OF  THE  TONGUE. 

Restraint — Lateral  recumbent  position  under  chloroform 
anaesthesia. 

ist  Step — Make  a  circular  incision,  convexity  forward, 
from  the  center  of  one  border  to  the  center  of  the  opposite, 
so  as  to  make  one-half  of  a  dove-tail  flap. 


ANIMAL   DENTISTRY.  245 

2nd  Step — Turn  the  tongue  upward  to  expose  the  lower 
surface,  and  by  a  similar  incision  complete  the  inferior  half  of 
the  dove-tail. 

3rd  Step — Close  the  wound  with  interrupted  sutures. 

After  Care — Feed  on  soft  diet  and  remove  sutures  in  eight 
days.  Amputation  of  the  tongue  produces  a  temporary  in- 
convenience in  the  prehension  of  liquids  but  is  otherwise  a 
harmless  operation.  The  above  method  leaves  a  flat  ex- 
tremity similar  to  that  of  a  normal  tongue. 

BIT-LUGGING. 

Definition — A  fault  or  habit  of  coach,  light-harness  and 
saddle  horses,  consisting  of  a  constant  or  periodical  tendency 
to  pull  heavily  upon  the  bit. 

Etiology — Dental  irregularities,  while  never  the  primary 
cause  of  the  habit,  irritate  the  seat  of  the  bit  and  render  its 
cure  impossible,  by  aggravating  the  animal's  temper. 

The  whip,  reinsman  or  equestrian  recognizes  three  dis- 
tinct classes  of  bit-luggers.  The  first  is  the  young  horse 
that  lugs  from  failure  to  understand  the  nature  of  the 
complicated  bitting  riggings  applied  for  the  first  time;  the 
second  class  comprises  the  mature  horse  that  has  developed 
the  habit  from  improper  training;  and  the  third  class  is  the 
lugger  by  nature  that  will  "pull  to  the  end  of  the  road"  in 
spite  of  the  punishment  inflicted  by  severe  bits. 

Complications — Bit  gnathitis  from  severe  pressure  and 
lacerations  of  the  buccal  surface  opposite  the  first  and  second 
superior  molars  from  friction  of  the  cheek  against  the  sharp 
enamel  points  are  certain  to  result  in  the  lugging  horse,  and 
in  turn  these  injuries,  which  are  frequently  of  no  small  pro- 
portions, are  prone  to  augment  a  bad  disposition. 

Treatment — The  treatment  of  bit-lugging  belongs  more 
to  the  domain  of  that  part  of  horse  training  known  as  "bit- 
ting" or  "mouthing"  a  horse  than  that  of  dentistry.     The 


246 


ANIMAL   DENTISTRY. 


latter  is,  however,  an  essential  feature  of  the  cure.  The 
proficient  teacher  of  the  horse  of  quality  will  always  demand 
that  the  anterior  extremities  of  the  molar  arcades  be  rid  of 
all  projections  that  may  irritate  the  buccal  surfaces,  as  a 
prerequisite  to  the  development  of  the  tactile  sense  of  the 
seat  of  the  bit.  The  dental  operation  for  this  purpose  con- 
sists of  trimming  and  filing  the  anterior  molars  smooth  and 
round  with  the  angular  cutter  and  file.  The  horse  must,  in 
addition,  be  made  to  become  gradually  accustomed  to  the 


Fig.  158.  Fig.  159. 

Bits  for  Confirmed  Luggers. 

A.  J.  L  C.  bit. 

B.  California  curb,  and  port. 

complicated  riggings.  In  the  "oach  and  saddle  horse  the 
dumb-jockey  is  indispensable,  to  develop  the  sensibility  of 
the  mouth.  It  should  be  equipped  with  a  soft  bit  one  to  one 
and  a  half  inches  in  diameter  to  develop  the  tactile  sense 
over  as  large  an  area  as  possible,  and  the  elastic  reins  should 
be  made  tighter  from  day  to  day  as  the  horse  becomes  more 
and  more  accustomed  to  its  mechanism.  Among  the  best 
coachmen  it  is  the  custom  to  equip  the  dumb-jockey  with  a 


ANIMAL  DENTISTRY.  247 

Straight  and  snaffle  bit  on  alternate  days.  The  light  harness 
horse  is  trained  to  the  bit  by  jogging  in  the  breaking  cart 
with  the  simplest  possible  riggings  and  all  forcible  restraint 
is  avoided,  the  aim  being  to  drive  the  youngster  with  a 
"light  hand"  and  teach  it  to  respond  to  the  slightest  touch 
instead  of  pulling  heavily  upon  the  bit. 

The  habitual  confirmed  lugger  that  has  formed  the  habit 
from  the  faulty  first  lessons  may  be  improved  by  handling 
in  the  same  manner,  and  in  addition  careful  attention  must 
be  given  to  the  wounds  of  the  mouth,  by  attending  to  the 
teeth  and  application  of  bits  that  will  control  the  horse  and 
at  the  same  time  inflict  no  further  injury.  If  the  jaw  is  sore, 
for  example,  the  covered  port  bit  may  be  serviceable  by 
protecting  the  wounded  part  and  transferring  the  punish- 
ment to  the  palate,  while  if  the  palate  is  sore  the  straight 
curb  may  be  applied,  and  the  lines  attached  to  the  lower  bar, 
the  object  point  being  to  prevent  the  unnecessary  aggrava- 
tion of  the  horse's  disposition.  In  the  light  harness  horse 
habitual  lugging  may  be  palliated  considerably  by  proper 
over-checking.  The  higher  the  horse  is  checked  the  easier 
it  will  be  to  control.  The  chin-overdraw  is  probably  the 
best  rigging  for  this  purpose,  owing  to  the  fact  that  the 
mouth  is  kept  closed,  and  that  there  is  no  over-check  bit  to 
irritate  the  interdental  space.  In  this  connection  it  must, 
however,  be  understood  that  what  will  answer  for  one  horse 
will  prove  useless  for  another,  and  vice  versa. 

The  confirmed  lugger  of  the  third  class  is  incurable  ex- 
cept by  giving  plenty  of  hard  work  to  lower  its  spirit,  which 
in  many  cases  may  impair  the  animal's  health  before  the 
habit  is  abandoned.  In  such  animals  more  than  the  others 
the  anterior  molars  must  be  free  from  points  to  mutilate  the 
soft  structures.  Beveling  the  first  inferior  molars  from  the 
gingival  margin  backward  over  the  crown  to  the  posterior 
border  of  the  table  has  often  been  practiced  for  the  purpose 


248  ANIMAL    DENTISTRY. 

of  preventing  the  I)it  from  lodging  against  the  teeth,  or  to 
prevent  grasping  the  bit  between  them,  but  this  operation  is 
never  efifectual  in  palHating  the  kigging  habit.  In  the  young 
horse  it  is  harmful  in  that  the  sensitive  dentinal  substance 
is  thus  exposed  to  the  surface.  Extraction  of  the  first  in- 
ferior molar  is  likewise  ineffectual. 

The  veterinarian's  full  duty  ends  when  all  sharp  points 
are  removed  from  the  molars,  and  when  appropriate  bits 
have  been  recommended. 

FACIAL  PARALYSIS. 

Synonyms — Bell's  paralysis.  Paralysis  of  the  lips.  Par- 
alysis of  the  seventh  cranial  nerve. 

Definition — A  partial  or  complete  unilateral  motor  par- 
alysis of  the  muscles  controlled  by  the  seventh  cranial  nerve. 

Etiology — Facial  paralysis  is  caused  by  injuries  to  the 
mastoid  region  where  the  seventh  nerve  leaves  the  cranial 
cavity.  The  contusion  is  sustained  by  hanging  in  the  halter 
in  the  recumbent  position,  striking  the  head  to  the  floor 
during  surgical  restraint  or  in  the  struggles  of  painful  dis- 
eases, or  from  blows. 

Symptoms — The  upper  lip  is  drawn  to  the  opposite  side, 
the  corner  of  the  lower  lip  is  dropped  so  as  to  show  its 
mucous  membrane,  the  nostril  draws  inward  during  inspira- 
tion and  in  the  severe  case  food  will  accumulate  in  the  cheek 
from  paralysis  of  the  buccinator.  When  the  paralysis  is  par- 
tial these  symptoms  are  less  pronounced.  Bilateral  facial 
paralysis  occurs  occasionally  when  both  sides  of  the  head 
are  contused  simultaneously  from  the  above  causes.  In  such 
cases  the  symptoms  presented  are  total  inability  to  move 
either  lip,  difTficulty  to  retain  food  between  the  teeth  and 
audible  inspirations  from  vapidity  of  the  nostrils. 

Differential  Diagnosis — Facial  paralysis  of  this  variety  is 
recognized  from  that  of  central  origin  by  the  sensibility  of 


ANIMAL  DENTISTRY.  249 

the  paralyzed  region  determined  by  pricking  the  parts  with 
a  pin. 

Treatment — Removal  of  the  cause,  liniments,  blister  and 
massage  along  the  course  of  the  seventh  nerve  w^ill  hasten 
the  recovery.  The  return  of  motion  to  the  parts  usually 
occurs  in  from  six  weeks  to  three  months.  If  the  injury  was 
severe  enough  to  destroy  the  continuity  of  the  axis  cylinders 
of  the  nerve  the  paralysis  may  continue  through  life. 


Fig.  i6o. 
Facial   Paralysis,  Right  Side. 

LACERATIONS  OF  THE  LIPS. 

Injuries  to  the  lips  are  of  considerable  import  in  the  horse, 
owing  to  their  prehensile  and  tactile  functions,  and  because 
of  the  unsightliness  of  a  permanent  division  of  their  con- 
tinuity. 

Etiology — Contact  with  sharp  objects.  Falls  on  hard 
pavement.    Dog  bites. 

Treatment — The  labial  wound,  which  includes  division 
of  the  border  of  the  lip,  requires  scrupulous  attention  in 
order  to  prevent  a  permanent  defect.     Perfect  disinfection 


250  ANIMAL   DENTISTRY. 

by  prolonged  irrii^atioii  with  weak  antiseptic  solution  is  the 
hrst  necessary  step.  1lie  wound  is  hrst  l)r()UL;iit  toj^-ether 
with  mattress  or  l)utton  suture  to  innn()l)ilizc  the  edges,  and 
then  closed  neatly  with  inlerrui)te<l  stitches.  A  thick  coat- 
ing- of  collodion  will  still  further  hold  the  parts  in  a])position 
and  serve  as  a  protection  ai^ainst  injur}-  and  infection.  The 
patient  must  be  fed  only  upon  gruel,  and  tied  on  the  pillar 
rein  for  at  least  six  days. 

RANULA. 

Definition — A  cystic  tumor,  belonging  to  the  class  of  re- 
tention cysts,  located  under  the  free  extremity  of  the  tongue. 

Susceptible  Animals — Dog,  cat,  ox  and  man.  Rare  in  the 
horse. 

Etiology — Ranula  is  generally  supposed  to  be  caused  by 
obstruction  of  one  of  the  ducts  of  the  sublingual  salivary 
gland. 

Diagnosis — Disturbed  prehension  and  mastication ;  pal- 
pation and  inspection. 

Treatment — Ranula  is  an  obstinate  disease  and  will  yield 
to  no  treatment  except  total  resection  of  the  entire  cyst  wall. 
Evacuation  of  the  contents  and  injections  of  irritants,  iodine, 
ammonia,  silver  nitrate,  etc.,  is  never  a  lasting  success. 

ACTINOMYCOSIS  OF  THE  TONGUE. 

(See  pages  218-19.) 

FOREIGN  BODIES  IN  THE  TONGUE. 

Pins,  needles,  tacks,  spicula  of  w-ood,  bones  or  iron  fre- 
quently become  lodged  deeply  into  the  substance  of  the 
tongue  near  its  base.  The  condition  is  manifested  by  dis- 
turbed mastication,  ptyalism,  rejection  of  partially  masti- 
cated food  and  disinclination  to  eat  freely.  The  penetration 
is  usually  well  under  the  base  of  the  tongue  at  a  location 
that  defies  detection  by  an  ordinary  palpation  or  inspection 


ANIMAL  DENTISTRY.  251 

of  the  mouth.  With  the  aid  of  a  mouth  specukim  palpation 
of  the  base  of  the  tongue  will  reveal  a  hard,  painful  area  in 
the  center  of  which  the  penetrating  body  will  be  found  pro- 
truding. The  treatment  consists  of  removal  of  the  foreign 
body  and  free  incision  across  the  infected  area,  followed  by 
mild  astringent  irrigations,  alum,-  borax,  sodium  chloride,  or 

boric  acid  solutions. 

FROST  BITES. 

Frozen  tongues  are  common  in  horses  having  the  habit 
of  protruding  the  tongue  while  driving  (tongue  lolling),  and 
not  infrequently  the  injury  thus  sustained  will  cause  necrosis 
of  the  entire  free  extremity.  Radical  treatment  must  be  de- 
ferred until  the  extent  of  the  frozen  area  becomes  apparent 
by  the  appearance  of  a  well  defined  line  of  demarcation. 
Amputation  will  hasten  recovery. 

LACERATIONS  OF  THE  CHEEKS. 

Lacerations  of  the  cheek  that  mutilate  or  divide  the 
buccinator  muscle  transversely  may  prove  a  permanent  detri- 
ment to  animals  by  destroying  its  necessary  elasticity  and 
contractility.  Constant  packing  of  food  in  the  cheek  or  re- 
striction to  the  movements  of  the  jaw  (cicatricial  trismus) 
are  frequent  results.  It  is  therefore  evident  that  these 
wounds  should  receive  intelligent  and  circumspect  attention. 
Careful  disinfection,  ingenious  closure  and  drainage,  and 
immobilization  of  the  parts  should  not  be  omitted  in  the 
treatment. 

TUMORS  OF  THE  LIPS  AND  CHEEKS. 

Carcinomata,  sarcomata,  actinomycosis,  warts  and  re- 
tention cysts  are  the  classes  of  tumors  usually  found  on 
these  organs.  The  growths  should  be  promptly  removed 
when  first  observed  to  prevent  their  diffusion  over  too  great 
an  area.     Pedunculated  warts  are  removed  by  surgical  abla- 


252  ANIMAL   DENTISTRY. 

tioii  or  ligation  and  the  diffuscnl  ones  hy  the  use  of  caustics. 
Copper  sulphate  and  arsenic  are  specific  against  warts.  Quit- 
man recommends  the  external  and  internal  use  of  Fowler's 
solution  as  a  specific  remedy  against  warts  covering  a  large 
surface.  Retention  cysts  usually  yield  to  simple  evacuation 
of  their  contents  by  a  free  incision.  Widely  spread  carcino- 
mata  and  sarcomata  are  incurable. 

LACERATION  OF  THE  TONGUE. 

Etiology — Traction  on  the  tongue  in  examining  the 
mouth  or  administration  of  medicines  is  the  common  cause 
of  laceration  of  the  fraenum.  The  body  of  the  organ  sustains 
injury  from  the  tie  chain,  iron  work  of  the  stall  or  by  being 
bitten  by  animals  in  the  neighboring  stall.  Sudden  fright 
while  sleeping  with  the  tongue  between  the  incisor  teeth  is 
the  probable  cause  of  the  mysterious  lacerations  of  the 
tongues  of  horses. 

Symptoms — Ptyalism,  disinclination  to  eat  and  drink, 
champing  of  the  jaws,  rejection  of  food  and  in  the  later  stages 
of  severe  lacerations,  fetor,  are  the  chief  symptoms. 

Treatment — Reposition  and  retention  of  the  lacerations 
with  sutures  and  amputation.  (Operation  of  amputation  see 
page  244.) 

Prognosis — The  tongue  is  well  nourished  and  will  heal 
well  when  sutured  if  the  blood  supply  is  not  too  greatly  dis- 
turbed. In  the  horse  amputation  of  the  free  extremity  causes 
only  temporary  inconvenience  in  the  prehension  of  liquids. 
In  the  ox,  dog  and  cat  loss  of  the  free  extremity  is  a  per- 
manent impediment  in  the  prehension  of  food. 

INFLAMMATION  OF  THE  TONGUE. 
Synonym — Glossitis. 

Etiology — Ingestion  of  irritants,  administration  of  irri- 
tating medicaments,  bit  bruises,  wounds  from  dental  irregu- 


ANIMAL   DENTISTRY.  253 

larities,  pin  punctures,  etc.  Specific  inflammations  of  the 
tongue  are  seen  in  actinomycosis  and  infectious  stomatitis. 

Symptoms — Same  as  lacerations  of  the  tongue. 

Treatment — Removal  of  the  cause;  soft  food;  mild  as- 
tringent irrigations;  alum,  borax,  boric  acid. 

Prognosis — Seldom  serious.  Necrosis  of  the  extremity 
may  require  amputation. 

ABERRATIONS  OF  THE  FUNCTION  OF  MASTICA- 
TION. 

The  common  aberrations  of  mastication  in  animals  are 
quidding,  ejecting,  bolting,  and  wadding  of  food. 

QUIDDING. 

Definition — Quidding  refers  to  that  aberration  in  which 
the  food  is  rolled  and  shifted  about  in  the  mouth  and  then 
finally  ejected  into  the  manger. 

Etiology  and  Symptoms — This  abnormality  occurs  in 
three  distinct  forms:  (i)  From  dental  irregularities  which 
produce  pain  when  attempt  is  made  to  masticate,  or  from 
some  lesion  of  the  temporo-maxillary  articulation.  In  these 
cases  the  food  is  not  comminuted,  but  is  simply  rolled  about 
in  the  mouth  and  ejected  in  large  masses  soaked  with  saliva. 
(2)  From  senile  dissolution  of  the  molar  arcades.  The 
molars  will  be  found  irregular,  short  in  the  crowns  and  fre- 
quently loosened  in  their  cavities,  and  the  food  will  be 
ejected,  as  in  the  former  cases,  because  the  molars  are  no 
longer  capable  of  performing  their  function.  (3)  From  a 
neurosis  affecting  the  nerves  of  deglutition.  In  this  variety 
of  quidders  the  food  is  finely  comminuted  before  being 
ejected  into  the  manger.  The  condition  is  seen  most  fre- 
quently in  horses  past  the  age  of  fifteen  years. 

Treatment — The  (-(uidding  horse  must  be  treated  ac- 
cording to  the  cause.     Sometimes  the  extraction  of  a  tooth, 


254  ANIMAL  DENTISTRY. 

the  tniniiiin!4'  of  an  elongation,  or  the  filinji;"  of  enamel  points 
which  wound  the  mucous  membrane,  will  promptly  cure  the 
aberration.  In  cases  of  senile  origin,  loose  teeth  arc  ex- 
tracted and  the  elongations  are  carefully  blunted  without 
further  disturbing  their  implantations.  The  food  should  be 
of  a  character  requiring  but  little  mastication.  Ground  corn, 
ground  oats,  cut  liay  and  bran,  given  dry,  is  the  most  suit- 
able diet  to  prolong  the  life  of  an  old  animal  so  afflicted. 

In  the  third  form  the  al)crration  may  often  be  overcome 
by  withholding  hay  from  the  food  allowance.  For  reasons 
difficult  to  explain,  hay  is  the  foodstuff  usually  ([uidded. 
Corn,  oats,  barley  and  bran  are  seldom  ejected  in  this  form. 
In  addition,  the  molars  must  be  well  examined  to  exclude 
them  as  the  cause  of  the  disorder. 

EJECTING  FOOD. 
The  ejection  of  food,  partially  or  completely  masticated, 
occurs  as  a  symptom  of  quidding,  from  causes  enumerated 
above,  and  from  abnormalities  of  the  mouth  or  teeth  that 
produce  pain  when  mastication  is  attempted.  A  split  molar 
tooth  that  wounds  the  buccal  surface,  carcinoma  of  the  pal- 
ate, sarcoma  of  the  jaw,  foreign  bodies  in  the  tongue  or 
cheek,  and  a  decaying  molar,  are  among  the  lesions  often 
responsible  for  this  condition. 

BOLTING  FOOD. 

Bolting  food  refers  to  the  aberration  of  eating  rapidly 
and  without  sufficient  comminution.  It  is  more  of  a  habit 
than  a  disease,  and  is  often  acquired  by  allow'ing  animals  to 
become  too  hungry.  The  nose-bag  method  of  feeding  is 
prolific  in  the  production  of  the  habit,  wdiich  is  still  further 
augmented  1)y  dental  disorders  that  induce  animals  to  avoid 
persistent  mastication.  The  habit  causes  indigestion  and 
colics,  and  results  in  the  loss  of  no  small  amounts  of  food, 
that  is  found  unmasticated   in   the   feces.      The    treatment 


ANIMAL  DENTISTRY.  255 

consists  of  first  attending  to  the  molar  teeth,  and  of  feeding 
in  such  a  manner  as  to  effectually  prevent  rapid  eating. 
Nose-bag  feeding  should  be  discontinued.  When  horses  are 
fed  in  harness  the  grain  should  be  spread  upon  the  ground 
over  a  large  surface.  In  the  stable  the  feed  box  is  taken 
out  and  the  grain  is  spread  over  the  entire  surface  of  the 
hay  manger  or  upon  the  floor  along  the  front  of  the  stall. 
Rapid  eating  under  these  circumstances  is  impossible  and 
the  habit  will  soon  be  abandoned.  Specially  appointed  feed- 
ing troughs  which  allow  the  food  to  flow  slowly  outward  as 
it  is  eaten  are  commendable. 

WADDING  OF  FOOD  IN  THE  CHEEK. 

The  accumulation  of  food  between  the  cheek  and  molar 
arcades  is  a  common  aberration.  It  is  caused  frequently  by 
a  serious  dental  disorder — fissured  molar,  loss  of  the  outer 
half  of  a  molar  crown,  elongation  that  wounds  the  cheek, 
etc.  The  most  obstinate  form  of  this  disorder,  however,  is 
due  to  a  defect  in  the  buccinator  muscle.  The  defect  may 
be  either  a  partial  or  complete  paralysis,  which  may  be 
either  co-existent  with  a  general  facial  paralysis  (see  facial 
paralysis,  page  248)  or  which  may  exist  as  a  circumscribed 
paralysis  of  the  muscle  itself.  The  cause  of  the  paralysis, 
when  circumscribed,  is  usually  a  trauma  of  the  buccinator 
branch  of  the  seventh  nerve  as  it  passes  superficially  over 
the  masseter.  A  lacerated  wound  over  the  masseter,  that 
divides  the  continuity  of  the  branches  of  the  nerve,  is  always 
liable  to  be  followed  by  this  condition. 

Impactions  of  food  in  the  cheek  are  also  caused  by 
wounds  of  the  buccinator  muscle  which  interfere  with  its 
normal  contractility.  A  trivial  surgical  or  accidental  wound 
may  disturb  the  function  of  this  highly  motile  muscle  suf- 
ficiently to  interfere  with  its  function  throughout  the  re- 
mainder of  the  animal's  life.     And  finally  cicatrices  of  the 


256  ANIMAL  DENTISTRY. 

buccal    mucosa    wliicli    dcstro}-    its    sensibility   arc    sufficient 
injury  to  1)C  followed  by  this  aberration  of  mastication. 

The  treatment  must  vary  with  the  cause.  When  due  to 
a  dental  disorder  a  cure  is  at  hand  by  correcting  the  defect. 
The  cicatricial  forms  are  incurable,  but  can  be  benefited 
somewhat  by  thoroughly  beveling  the  buccal  border  of  the 
superior  molar  arcade.  The  paralytic  form  is  either  curable 
or  incurable,  according  to  the  severity  and  duration  of  the 
injury. 


INDEX 


y^BERRATIONS    of    the    Func- 
tion of  Mastication 253 

Abnormal  Eruption  of  the  Teeth. 173 

Accidents    160 

Acquired  Elongation  of  Molars..  185 

Actinomycosis     218,  251 

Age — Determination    of 74,  113 

Age— Birth  to  One  Year 74 

Age — One   to   Two   and  One-Half 

Years     75 

Age — Two   and   One-half  to   Five 

Years    SO 

Age — Five  to  Eight  Years 89 

Age — Nine  to  Old  Age 89 

Age — T  w  e  n  t  V     to     Twentv-five 

Years     .  .  . ". .' 113 

Age— Old  Age   113 

Age — Routine  of  Examination  to 

Determine  a  Horse's 113 

Alveolar   Cavity    48 

Alveolar   Margin — Receding   of .  .    73 

Alveolar   Periostitis    152 

Alveolar  Plate — -Removal   of   Ex- 
ternal     167 

Alveolo-Dental  Periosteum.  ...  19,  24 

Alveolo-Nasal  Fistula    166 

Amputation  of  the  Tongue 244 

Animal    Dentistry — -Scope    of....    15 

Anomalies — Artificial     119 

Anomalies  of  the  Teeth — Natural 

and    Artificial    117 

Anorexia    157 

Aphtha — Contagious     227 

Aphthous  Stomatitis    227 

Apical   Foramen    47 

Application      of      Gutta      Percha 

Plugs    238 

Arcades — Inferior    34,     35 

Arcades- — Superior     33,     35 

Artificial  and  Natural   Anomalies 

of  the  Teeth   117 

Artificial   Anomalies    119 

n  ELL 'S  Paral vsis   245 

Beveling  of  the  Molars 182 

Beveling   of    Left    First    Inferior 

Molar   199 

Beveling  of  Right  First  Inferior 

Molar    198 

Bishoping    120  to  126 

Bites— Frost     251 

Bit  Contusions 214 

Fiit  Onathitis   214 

Hit  Lugging 245 

Bit   Sores    214 


Blood   Vessels    19 

Blunting  to   Left   First   Superior 

Molar   198 

Blunting  to  Right  First  Superior 

Molar 197 

Bodies  in   the  Mouth — Foreign.. 210 

Bolting  Food    254 

Brachygnathism     179 

QANINES.17,  51,  54,  61,64,  65,    127 
Canine   Teeth   of  the   Horse 

27,   38,   30,   175 

Carcinomata     251 

Carcinomata  of  the  Palate 217 

Caries    152,  172 

Caries  Dentium   172 

Catarrh — Chronic      and     Primary 

Chronic  Nasal    231 

Catarrh — Persistency    of    166 

Catarrh — 'Secondary       Chronic 

Nasal    231 

Champing    241 

Character  of  the  Food 119 

Cheeks — Lacerations  of  the 251 

Cheeks— The     130 

Cheeks — Tumors  of  the  Lips  and. 251 

Chin — Prominent     181 

Chin — Receding     179 

Chronic  Nasal  Catarrh 231 

Chronic   Nasal   Catarrh — Primary 

and  Secondarv 231 

Chronic  Perforation  of  the  Skull.236 
Chronic  Rhinitis — Unilateral.  .  .  .231 
Chronic  Sinuses  of  Lower  Jaw.. 166 

Cement    19,     22 

Central   Incisors    

49,  51,  52,  54,  56,  60,  63,  64,     65 

Common  Enamel  Germ 47 

Complete  Denture  of  a  Horse...   18 

Contagious   Aphtha    227 

Contagious  Pustular  Stomatitis.  .227 

Contusions — Bit     214 

Corner  Incisors   

....50,  51,  52,  54,  57,  61,  64,    65 

Cribbing    239 

Crowns — Polishing  the    120 

Crowns — Sliorteuing  of 120 

Crusta  Petrosa 19,  22,     23 

Cupping  the  Incisor  Teeth 123 

Oups  of  the  Infundibula 118 

Cups — Renewal    of   the 120 

Cuticle  of  tiie  Enamel 22 

Cysts— Dental     177,  222 

Cysts— Retention    230,  251 

257 


2o8 


INDEX 


QKCAVKI)  Teeth    152,  172; 

Decayoil  I'ootli — Fracture  af.HiO 

Def^liititioii   Piiouinoiiia lOT, 

Dental  Arterv — Ileinorrhage  from 

the    ....' 161 

Dental  Cysts 177,  222 

Dental   Dia^niosis    l.*?:? 

Dental  Evolution  and  Retrofres- 
sion  A]ii)lie(l  to  Determina- 
tion of  Ape — Summary  of.  .  .    74. 

Dental    Folliele    '. 48 

Dental   Fistula    166,  224 

Dental   Halter    148 

Dental  Instruments — Their  Uses.l.So 

Dental    Pajiilla    47 

Dental    Teratomata    222 

Dental    Tissues — Arrangement   of 

in  Incisor    24 

Dentigerous   Cysts    222 

Dentinal   Substance    47 

Dentine    19,   20,     23 

Dentitis    152 

Denuding     210 

Destruction   of   Temporary   Tooth 

by  the  Permanent    09 

Determination  of  Age 74 

Determination     of    Age — Routine 

of   Examination   to 113 

Diagnosis — Dental     133 

Digastricus  Muscle — The   131 

Diseases     and     Irregularities     of 

Teeth 152 

Dislocation  of  tlie  Temporo-Max- 

illary  Articulation    213 

Divisions  of  a  Tooth   19 

Dog— Denture  of.  .39,  40,  41,  42,     43 

Dog  Speeulums 174,  175 

Dog — Temporary   Teeth    of 54 

Dogs — Ulcerative  Gingivitis  of.. 229 

jgJECTING   Food    254 

Elongation   of  the  Molars — 

Acquired     185 

Elongation — Operation  of  Out- 
ting     186 

Elongations  of   the  Incisors 206 

Embryonic   Evolution    44 

Enamel    19,     31 

Enamel— Cuticle  of  the 22 

Enamel— Erosion  of  the   208 

Enamel  Germ — Common     47 

Enamel  Organ   47 

Enamel    Points    187 

Enamel   Points  of  Ilerbivora  .  .  .  .  187 

Erosion   of  the  Enamel    208,  210 

Eruptions  of  the  Teeth 117 

Eruptions  of  the  Teeth — Abnor- 
mal    175 

Evolution  and  Retrogression  of 
the  Teeth  Tabulated   ...124,125 

Evolution — Embryonic     44 

Evolution  of  Permanent  Teeth .  .  58 
Evolution  of  Tem])orary  Teeth..  49 
Examination  of  the  Mouth 190 


'Extraction     of     the     Canines     of 

Horses    172 

PLxtraction    of  the   Incisors 171 

Extraction  of  tlie  Teeth  of  Dogs.  174 

Extraction   with  Forceps 159 

Eye  Teeth 202 

-p  ACl  AL  Paralysis    245 

ft         Facial     Sinuses  —   Purulent 

Accumulations  in    231 

Fang    47 

File— Flat  and  Rasp 137 

Fissuring  of  the  Molars 209 

Fistula— Alveolo-Nasal     166 

Fistula— Dental    166,  224 

Fistulae— Mastoid     222 

Float— The    Angular    136 

Float— The    Straight    136 

Floating  and  Filing 191 

Floating  and  Trimming  Molars.. 189 
J^oating  the  Teeth  of  the  Ox... 202 
Floats     and     Files— Methods     of 

Using   on   INFolars    192 

Floats  and  Float  Blades 135,  136 

Follicle— Dental     48 

Food-Bolting    2.54 

Food — CHiaracter  of  the    119 

Food — -Ejecting    254 

Food — Wadding  of  in  the  Cheek. 225 

Foramen — Apical     47 

Foreign  Bodies  in  the  ISfouth.  .  .  .210 
Foreign  Bodies  in  the  Tong-ue .  .  .  250 
Formulae  of  Temjiorary  and  Per- 
manent Dentures  of  Animals 

66,     67 

Fracture   of  Decayed   Tooth 160 

Fracture  of  the  Interior  Maxilla.211 

Fracture   of  the   Teeth 209 

Fractured  Jaw 214 

Fractures   of  the  Premaxilla  and 

Superior   Maxilla    213 

Frost  Bites   251 

Functions  of  the  T.eeth 127 

QERM— Common  Enamel   47 

Gingivae    19 

Gingival    Cushions    45 

Gingivitis  of  Dogs— Ulcerative.  .229 

Gleet— Nasal    231 

Glossitis    252 

Gnathitis— Bit   214 

(iutta      Percha      Plugs — Applica- 
tions of   238 

J-jAP.lTUAL   Protrusion    of    the 

Tongue    244 

Ilal)it.ual   Ptvalism    241 

Hard   Palate— The 130 

Hard   Tissues   19 

Hemorrhage  from  the  Dental  Ar- 
tery  161 

Hemorrhage — Palatine    160 

Horse — Complete  Denture  of 18 

Horse — Temporary  Teeth  of 49 


INDEX 


259 


JXCISOE   Nippers    143 

Incisor  Teeth  of  the  Ox. 37,     51 

Incisor  Teeth — Shedding    of 175 

Incisor   Teeth — Shortening.  .123,   206 
Incisor      Teeth — Polishing,      Cup- 
ping and  Staining  the 123 

Incisors     18,  127 

Incisors — Central     

49,  51,  54,  56,  60,  63,  64,     65 

Incisors — Corner    

50,  52,  54,  57,  61,  64,     65 

Incisors — Elongation   of    206 

Incisors — Extraction    of    171 

Incisors — Inferior    51 

Incisors — Intermediate    .  .51,  57,     64 

Incisors — Lateral    

50,  51,  54,  56,  60,  64,     65 

Incisors — Permanent  of  Horse.27,    28 
Incisors — Permanent      of      Eumi- 

nants    34 

Incisors — Temporary  of  Horse.  .  .   50 

Infectious    Stomatitis    227 

Inferior  Arcades    34,     35 

Inferior  Incisors   51 

Inferior  Maxilla — Fracture  of  the.211 

Inferior  Maxillary     129 

Inferior  Molars    ". 32,33,34,     39 

Inferior  Molar   of  Ox 38 

Inflammation  of  the  Tongue 252 

Infundibula — The   118 

Infundibula — Cups  of  the 118 

Inf  undibulum    19^     21 

Inspection  of  the  Mouth '.135 

Instruments — Dental — Their  Uses.135 

Intermediate  Incisors   51,     57 

Introduction     13 

Irregularities     and     Diseases     of 
Teeth    1.52 

J  AW — Fractured     214 

Jaw — Prominent     181 

Jaw — Receding    179 

Lacerations  of  the  Cheeks.251 

I^aeerations  of  the  Lips.  .  .  .249 

Lacerations  of  the  Tongue 252 

Lampas    230 

Lateral    Enamel   Projections 187 

Lateral    Incisors    

50,  51,  54,  56,  60,  '64,'   65 

Lips  and  Cheeks— Tumors  of  the. 251 

Lips — Lficerations  of  the 249 

Lijts — I'aralysis  of  the 245 

Tx)l]ing — Tonfiue    244 

fiUgging — Bit    245 

Lumi)y  Jaw   218 

^  AROINS  of  the  Teeth 20 

Masseter   Muscle — The    ...130 

Mastication — Mechanism    of 129 

Mastoid    Fistulae    222 

Maxillary — The   Inferior    127 

Maxillary — The  Suj)erior   127 

Maxillo-Xasal   Notch    130 


Mechanism   of   Mastication 129 

Merillat's  (Prof.  Ed's)  Operation 

for     Closing     Chronic     Skull 

Perforations    237 

Micro-Organisms    173 

Molar  Crown  Cutter    144 

Molar  Cutter — Angular     142 

Molar  Cutter — Or     T  r  i  m  m  e  r — • 

Closed    1.37 

Molar  Cutter — Open     138 

Molar  Extractor — Closed    141 

Molar  Extractor — Open    142 

Molar  Separator    140 

Molar — Fourth     .54 

Molar — Natural   Cavities   of 23 

Molar  T,eeth     176 

Molars   18,  30,  127 

Molars — Acquired  Elongation  of.  185 

Molars — Fissuring    of    the 209 

Molars — Fourth  and  Fifth. 62,  64,  65 

Molars — Sixth     63,  64,  65 

Molars — First,  Second   and  Third 

50,  54,  57,  61,  64,     65 

Molar.s — Inferior    32,33,34,     39 

Molars — ^Permanent  of  Ruminants  36 

Molars — Projections    on 184 

Molars — Splitting  of  the 200 

Molars — Superior    30,  31,     32 

Molars — Trimming    and    Floating 

189,  191,  192 

Mouth — Inspection  of  the 135 

Mouth — Palpation  of  the 133 

Mouth — Sarcomata  of  the 217 

Mouth  Speculum 144,  145,  146 

Muscle — The  Digastricus    131 

Muscle — Ti^e    Masseter 130 

Muscle — The  Pterygoid  Externus.131 
Muscle — The  Pterygoid  Internus.131 
Muscle— The  Sterna  Maxillaris.  .131 
Muscle— The  Stylo  Maxillaris  ..131 
Muscle — The  Temporalis    131 

j^ASAL    Catarrh— Chronic    Pri- 
mary Chronic  and  Secondary 

Chronic    *.  231 

Nasal   Gleet    231 

Natural  and   Artificial  Anomalies 

of  the  Teeth    II7 

Neck     47 

Necrosis  of  the   Teeth   of  iferbi- 

vora    152,  154 

Nerve     and      Blood      Supjdy     of 

Horses '  Teeth    " 25 

Nerves   19 

Nippers — Incisor   143 

Nomenclature  of  the  Teeth IS 

Q  DONTOM ATA    1  78 

Oi)ening  of  the  Skull 1()4 

Operation  of  Cutting  Klongations.186 
Operation  of  Trimming  and  Float- 
ing Molars    189 

Osteo-I>entine     70 

Osteoma  of  the  Maxilla 176 


260 


INDEX 


()stoom:it;i   of  Siijiciior  ^Sfaxilla  .  . -K! 

Ox — Floatiiif,'   TtH'th    of lin-J 

Ox — Teinporarv   Teetli   of ")1 

Ozena   ' 2;n 

PALATK— ("arcinoniata  of  the. 217 

*■        I'alatc— Tlie    Hani    130 

T'alatiiic    Honiorrhajjc    160 

I'al|patioii  of  the  Mouth 133 

I'apina— Dental     47 

Paralysis — Bell's,   Facial,    of   the 
Lips,  of  the  Seventh  Cranial 

Nerve    248 

Parrot  Mouth    179 

Parvi-rnathism    182 

Perforation      of      the      B  k  u  1  1 — 

Chronic    236 

Pericementitis    152 

Peridentitis    152 

Permanent  Incisor  Teeth  of  Horse 

27,     28 

Permanent  Incisors  of  Ruminants.  34 
J*erniaiient  Molars  of  Ruminants.  37 
Permanent  T.eeth — Evolution  of.  58 
Permane7it  Teeth — Number  of .  .  .  65 
Permanent     Teeth — Retrogression 

of    68 

Persistency  of  Catarrh 166 

Pijr — Temporary  Teeth  of 52 

Polishing  the   Crowns 120 

Polishing  Incisor  Teeth 123 

Poll    Strap    149 

Predisposing   Causes    173 

Preface    9,     10 

Prehension    128 

Premaxilla — Fracture   of  ,the.  .  .  .213 

Premaxilla— The    129 

Primary   Chronic  Nasal   Catarrh. 231 

Prognathism    181 

Projection   on  the  First   Superior 

and   Sixth   Inferior  Molars..  184 
Projections  on  Superior  Corners,  185 

Prominent  Chin     181 

Prominent  Jaw    181 

Protrusion    of    the    Tongue — Ha- 
bitual     244 

Pterygoid  Externus  Muscle — The.131 
Pterygoid   Internus  Muscle — The.131 

Ptva'lism— llaliitual    241 

Pulling    241 

Pulp     19,  24,     47 

Pulpitis    152,  153 

Purulent  Accumulations  in  Facial 

Sinuses    231 

Pustular    Stomatitis — Contagious.227 

QlTIDDING   253 

P^ANULA    250 

Receding   Chin    179 

Receding  Jaw    179 

Receding  of  Alveolar  Margin.  ...  71 
Reining— Side    242 


K.  mnant  Teeth    202 

h'einoval     of     I'lxternal     Alveolar 

Plate    167 

Removal    of    Teeth    by    Sjilitting 

with    Chisel    ." 170 

Renewal   of  the   Cups 120 

Repulsion    of    Teeth    with    Punch 

and  Mallet   161 

Repulsion  of  the  Tooth 165 

Restraint     148 

Retention  Cysts 2.30,  251 

Retrogression    and    Evolution    of 

the  Teeth  Tabulated  ...  124,  125 
Retrogression    of    tlie    Permanent 

Teeth    68 

Retrogression  of  Temporary  Teeth  6.S 

Rhinitis — Unilateral   Chronic 231 

Routine       of       Examination       of 

Horses'   Mouth   to  Determine 

the    Age    113 

g  ARCOMATA    251 

Sarcomata  of  the  Mouth... 217 

Scissor  IMouth    182 

Search  Light   134 

Secondary  Chronic  Nasal  Catarrh. 231 

Septicaemia    167 

Seventh    Cranial    Nerve — Paraly- 
sis  of    !  .248 

Sharp    Teeth    187 

Shedding  of   the    Incisor  Teeth.. 175 

Sheep — Temporary  Teeth  of 56 

Shortening  of  the  Crowns     120 

Shortening  of  the  Incisor    Teeth .  .123 

Side   Reining    242 

Sinuses — Chronic   of  Lower  Jaw.  166 
Skull — Chronic      Perforation      of 

the    236 

Skull— Opening  the    164 

Skull— Treidiining    the    162 

Skull — Trephining   for   Nasal   Ca- 
tarrh     2.33 

Slobbering    241 

Soft    Tissues    19 

Sores— Bit     214 

Splitting  of  the  Molars 209 

Staining  the  Incisor  Teeth 123 

Sterno   Maxillnris   Muscl(^-The.  .  131 

Stomatitis— Ai)1ithous    227 

Stomatitis — ^Contagious    Pustular.227 

Stomatitis — Infectious     227 

Stomatitis— Traumatic     226 

Structures  of  the  Teeth 19 

Stylo   Maxillaris— The    131 

Summary     of     Dental     Evolution 
and  Retrogression  Applied  to 

Determination   of   Age 74 

Superior     Maxilla — Fractures     of 

the    213 

Superior  Arcades    33,     35 

Superior  Maxillary     129 

Superior  Molars    '. 30,  31,     32 

Superior  Molar  Arcade  of  Ox...   38 
Superior  Molar  Table  of  Ox 39 


INDEX 


261 


Surfaces  of  the   Teeth 19 

Supernumerary   Teeth    202,204 

Supplementary   Teeth    202 

Susceptible   Animals    173 

XABLE    of    Superior   Molar    of 

^      Ox     39 

Tabulated   Evolution    and    Eetro- 

gression   of  Teeth 124,  125 

Tartar    208 

Teeth — Abnormal     Eruptions     of 

the    175 

Teeth — Anomalies  of  the  Natural 

and    Artificial    11" 

Teeth — Canine  of  Horse.. 27,  28,  175 

Teeth — Decayed    152,  172 

Teeth — Diseases     and     Irregulari- 
ties of   152 

Teeth— Eruption   of   the 117 

Teeth — Evolution   and   Eetrogres- 

sion  Tabulated   124,  125 

Teeth— Evolution   of   the 44 

Teeth — Evolution   of   the   Tempo- 

rarv    -49 

Teeth—Eve     202 

Teeth— Fracture   of  the 209 

Teeth — Function  of  the 12; 

Teeth — Incisor     of     Horse     (Per- 
manent)     27,     2S 

Teeth  of  Ruminants.  .36,  37,  38,  3! 
Teeth  of  the  Dog. 39,  40,  41,  42,     4a 

Teeth— Margins  of  the 20 

Teeth— Molar   18,  30,  127,  176 

Teeth — Nerve   and   Blood   Supply 

(Horses')     25 

Teeth — Nomenclature  of  the....  18 
Teeth — Number  of  Permanent...  65 
Teeth — Number  of  Temporary.  .  .   65 

Teeth — Repulsion   of    161 

Teeth — Retrogression    of    Perma- 
nent        68 

Teeth — Retrogression    of    Tempo- 
rary       68 

Teeth— Structure  of  the 19 

Teeth— Supernumerarv     202,  204 

Teeth— Textures  of  the 118 

Teeth— Ulceration   of    172 

Teeth— Wolf    202 

Temporalis  Muscle — The   131 

Temporary  Teeth. — Evolution  of.  49 
Temporary   Teeth — Number   of.  .    65 


Temporary    Teeth — Retrogression 

of    68 

Temporo-Maxillary       Articulation 

— Dislocation'  of    213 

Teratomata— Dental     222 

Texture  of  the  Teeth 118 

Tie  Ropes   149 

Tissue — Interdental    Cancellated.   48 
Tissue — Ossified    Connective    ....   48 

Tissues — Hard    19 

Tissues— Soft     19 

Tongue     130 

Tongue — Foreign    Bodies   in 2.50 

Tongue — Habitual    Protrusion    of 

the    247 

Tongue — Inflammation    of    the... 252 

Tongue — Laceration   of    252 

Tongue  Lolling   244 

Tongaie — Operation     of     Amputa- 
tion of  the 244 

Tooth — Division   of   a 19 

Tooth  Chisel— The    144 

Tooth — Rei)ulsion  of  the 165 

Tooth— Self   Extraction   of   the..  153 

Tooth  Tumors    176 

Traumatic   Stomatitis    226 

Trephining   the    Skull 162 

Trephining    the    Skull    for   Nasal 

Catarrh    233 

Trimming  and  Floating  Molars.. 189 
Tumefaction   on   Superior   Maxil- 
lary      216 

Tumors  of  the  Lips  and  Cheeks. 251 
Tumors  of  the  Alueous  Membrane 
of  the  Mouth    230 

Ulcerations  of  Teeth 172 

Ulcerative       Gingivitis      of 

Dogs    229 

Undershot    181 

Unilateral    Chronic    Rhinitis 231 

Wadding     of    Food     in     the 

*'      Cheek    255 

Warts    251 

Wear  from  Miastication 10 

Williams '   Operation    167 

Wind  Sucking   239 

Wolf   Teeth    202 

Wolf  Teeth   Forceps 140 

Wolf   Tooth    Separator 140 

Wooden   Tongue    219 


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